# Beginner question - Using lathe as a mill?



## kuksul08 (Oct 22, 2011)

As many of you know, I just got that lathe and it's my first heavy duty machine tool. Of course, I'm already thinking about projects I want to do and sadly they mostly require a mill. I'm not running a machine shop here, it's just for personal hobby use, so I don't know how feasible buying a whole new machine is.

So something crossed my mind, and I don't know whether it's common, safe, or even possible. Can I use the lathe as a mill? That is, put an end mill in the chuck and clamp the part in the cross slide (lacks precise vertical motion). I could perform simple mill operations this way, but I would probably need an attachment that is a vice positioned vertically with a dial of some sort.

I found this information on the topic: http://www.astronomiainumbria.org/a...ca/easyweb.easynet.co.uk/_chrish/tmilling.htm

Any advice?


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## Anglepoise (Oct 22, 2011)

Milling on a lathe is entirely feasible for small jobs. You can purchase devices that attach to the cross slide and give you the vertical movement.

However before spending $$$$$$ get a copy of the book "Milling Operations in the Lathe" by Tubal Cain. My copy was $4.95 and I am sure you can find a copy online.Gives you everything you will need to know and photos of setups.


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## Th232 (Oct 22, 2011)

Seen it done, and I once saw a lathe where someone had rotated the cross-slide to get movement in the z axis. Looked kinda weird though.

You may find you have a lack of space/travel in certain directions though....


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## precisionworks (Oct 23, 2011)

The easiest way to obtain a milling attachment is to buy the ready to finish kit from MLA.


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## precisionworks (Oct 23, 2011)

This gives vertical adjustment + T-slots for clamping the part.


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## unterhausen (Oct 23, 2011)

you will occasionally see a milling attachment on ebay. I've done milling on a lathe, but it's not much fun.


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## kuksul08 (Oct 23, 2011)

That's pretty cool, and pretty affordable. It looks great for small jobs until I can afford a proper mill one day.


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## gadget_lover (Oct 24, 2011)

You can do many milling operations by mounting the work sideways in the chuck and then facing, drilling or boring as needed.

For instance you can make a 6 sided head for a flashlight by mounting it sideways 6 times and facing it each time.

Daniel


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## precisionworks (Oct 24, 2011)

> That's pretty cool, and pretty affordable. It looks great for small jobs


Because it is an unfinished casting you'll need a mill (or access to one) to complete the kit.



> you will occasionally see a milling attachment on ebay.



Like this one


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## kuksul08 (Oct 24, 2011)

Oh yeah, I missed that part about the casting when I read it the first time.

That one on eBay looks nice. To mount it to the lathe, do you use a large bolt through the center of the fork? How can I tell if it would fit or not?


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## precisionworks (Oct 25, 2011)

The 250V fits 9"-12" swing machines while the 400V fits 12"-16" machines.


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## gadget_lover (Oct 25, 2011)

The poor man's version (works with lathes that are not too tiny).

remove toolpost from compound.
bolt small machinist vice to compound. http://www.shars.com/products/view/110/Precision_Toolmakers_Vise_212quot
Remove compound from cross-slide. 
Mount angle plate to cross slide where compound was. http://www.shars.com/products/view/544/Angle_Plate_2x2x2quot
Mount compound to the vertical side of the angle plate.

You now have the same basic thing. Compound for up/down/tilt. Cross slide for in/out. 


Daniel


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## LeGranDuc (Nov 23, 2011)

I have done it the other way round. Turning inn a mill. Worked out well. Machined a new bolt for my painball marker.

I had to do it that way because i dont have training in any of the lathes. The company that i work for moved and merged with another company, so the lathe i could operate got sold off.
I am always amused when looking at non-machinist's machines. So tiny. Much like the lathe used in the JetBeam RRT3 XML "making off video".
That lathe has an odd tool-holder.


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## gadget_lover (Nov 23, 2011)

Tiny is one way of looking at it. Another is "portable" or "fits where I need it" or "big enough for what I plan to do". And of course, a tiny one is "better than no lathe at all". 

Of course, I'd like a nice big 12x36.  Not in the cards at the moment.

Daniel


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## kuksul08 (Jan 8, 2012)

I am looking into this idea again since buying a whole mill is not feasible due to cost and space limitations. I'm still a little confused about compatibility. How do I know if it will fit onto my compound slide? My lathe is a 12x36 - does that mean it is a _12" _size?


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## precisionworks (Jan 8, 2012)

> My lathe is a 12x36 - does that mean it is a _12" _size?


That's correct since a lathe is normally sized by the largest part it can swing.


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## BVH (Jan 9, 2012)

I'm thinking about getting one of these milling attachments. A mill is not in the cards right now and as a simple example of what I'd like to do - I picked up a Holdridge 3D Radii kit on Ebay and I need to make a simple T-Nut to hold it down. A while back, my QCTP T-Nut blank cost me $60.00 for machining (1 hr min). It was a simple job I could have done on the lathe with an attachment. So now I find myself in the same position again. Another $60 for another T-Nut or pick up a good quality - ready to install milling attachment. Can someone recommend one or more high quality, versatile, ready to install units sized for the PM1236? (Then again, I'll probably have to pay to have a T-Nut machined for the milling attachment - Gotcha again!) Is the Palmgren a good quality unit? I don't see much else when searching other than the small units for the siegs, etc.


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## precisionworks (Jan 9, 2012)

> Is the Palmgren a good quality unit?


Palmgren makes both a USA line & and imported line but both are well finished. As long as you remember that the milling attachment is esentially a drill press vise & take the same cuts that you would take using a drill press vise on a Bridgeport it should do fine. Feed gently with shallow DOC and you'll be able to mill quite a few parts. Problem is that once you start milling you will really want a mill :nana:


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## kuksul08 (Jan 9, 2012)

When you say it's essentially a drill press vise, what's the difference between that and a traditional milling vice?


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## precisionworks (Jan 9, 2012)

> what's the difference between that and a traditional milling vice?



A milling vise has a massive moving jaw & a huge screw with long handle capable of applying tons of force to the part. A DP vise has a smaller moving jaw & a smaller screw so the jaw cannot be tightened as much.

Palmgren 6" DP vise:





Palmgren 6" milling vise:





As long as the part can be securely tightened in the milling attachment & the milling forces are not so great as to rip the part out of the vise it will work well.


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## BVH (Jan 9, 2012)

precisionworks said:


> .................. Problem is that once you start milling you will really want a mill :nana:



Yep! Not long after I posted, I did some thinking. I'm still drill press'less. So...a good 12-13" bench style drill press....$450 and a Palmgren 4"....$450. Then I looked at the Little Machine Shop Mini Mill. (I think it might be an X2?) About $1100 with a nice tooling package to get started. Then looked at a Seig 3 and SX3 and Grizzly equivalents. This is the same thing I did with the lathe! Definitely not the best idea to buy a separate drill press and milling attachment for almost the same money as a small mill.


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## kuksul08 (Jan 9, 2012)

You have a point^

At the same time, I feel like I'd rather do the vertical attachment on the lathe until I can save for a proper CNC mill. I mean, you're still pretty limited with a manual mill aren't you? Being an engineer, I send out a lot of parts to be fabricated, and the common use of CNC has leveled the playing field price-wise. A piece with complex curves costs little more than something with nice standard sizes and straight edges.


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## gadget_lover (Jan 9, 2012)

Your cross slide has slots, right? Since that is the case, you can mount things directly to the cross slide. A standard nut will often work in place of a t-nut, though it's a hassle to keep them from turning when you tighten them.

For simple cuts (like a T-Nut) you can cobble together a fixture by bolting an angle plate to the cross-slide, then bolt a chunk of steel to the angle plate at the appropriate height. Put an end mill in the chuck (although a collet is preferred ) and you can mill nice straight lines. 

You can true up the sides of the nuts by mounting them in a 4 jaw and face it. That's functionally the same as using a fly cutter.

I only threw that out as a way to bootstrap the process of making a T-nut so you can mount the milling attachment to make a T-nut. A milling attachment is the best way to go. 

Dan


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## kuksul08 (Jan 10, 2012)

No, my cross slide has a circular shaped slot with two nuts that sit inside the slot. The compound slide rotates in this groove and you can tighten it down.

You can see the groove in this picture (with a lot of extra crap):






and how the compound slide sits, here:


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## precisionworks (Jan 10, 2012)

> my cross slide has a circular shaped slot with two nuts that sit inside the slot


Buy an angle plate with a base slightly wider than the hole-to-hole spacing on the cross slide. Drill two holes in the angle plate that match the hole spacing in the circular groove & use the existing bolts to secure the plate to the cross slide. Mount the part to the angle plate with step clamps/or bolt through the back/or mount a vise on the angle plate/etc.



> you're still pretty limited with a manual mill aren't you?


A mill is a mill whether the dials are turned by hand or by drive motors. CNC equipment is great when a number of identical parts need to be run but a CNC mill can do only one operation that cannot be done on a manual mill - circular interpolation. If the part requires a circular slot (that cannot be done on the lathe) or if it requires an elliptical slot or some other unusual shape the CNC control will do that.

Unless more than ten parts need to be run I do them on the manual mill. Much over ten, especially if complicated, go to a CNC shop. Here are some examples of manual mill work:

Positioning of trit slots using a Super Spacer for angular location:





Corner slot location:





Six slots on each end:





Slotting a D10 piston:





And another D10 piston:





On those jobs a CNC mill would offer no advantage unless a programmable rotary servo indexer was used ... and even the smallest 5C indexer from Yuasa costs over $9000


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## kuksul08 (Jan 10, 2012)

That's a great idea, and good work! I guess what I was thinking was that you could do a lot more with a CNC with fewer tools simply due to the interpolation. It _is_ a big price to pay for the convenience though.


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## kuksul08 (Jan 12, 2012)

During my search for a proper vertical slide solution, I will also need to get some basic tools for milling. I'd like to keep it simple for now and get the most essential tools. From my limited milling experience, the 1/2" 4-flute HSS end mill seems like a really common choice, especially since I primarily do aluminum and plastics.

So what milling tools do you find yourself using most often?


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## gadget_lover (Jan 12, 2012)

In general, you will use different end mill sizes based on what you are cutting and how much power your machine has.

The longer the tool, the more deflection so the more inaccurate. A bigger diameter tool is always stiffer. But you can not use a 1/2 inch end mill to cut a 1/4 inch wide slot.... unless you weld a lot.

Daniel


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## precisionworks (Jan 12, 2012)

kuksul08 said:


> During my search for a proper vertical slide solution, I will also need to get some basic tools for milling. I'd like to keep it simple for now and get the most essential tools. From my limited milling experience, the 1/2" 4-flute HSS end mill seems like a really common choice, especially since I primarily do aluminum and plastics.
> 
> So what milling tools do you find yourself using most often?



For milling that is not rigidly fixtured (like lathe milling) cobalt gives the best combination of toughness & hardness. Costs a little more than HSS, costs less than solid carbide, tougher than nails & can be run at decent sfpm.


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## kuksul08 (Jan 17, 2012)

On Saturday I did a little test on my lathe because I needed to drill a hole in some aluminum L plate. I put a 1.625" hole saw in the chuck and mounted the L plate to my cross slide using C clamps. It worked really well... I'm surprised. Even more motivation to turn this thing into a mill.

So I have been doing a bunch of research and I think I've decided on two bits to get me started. Hopefully I can do the most common operations with:
-1/2" 2-flute HSS or cobalt end mill for use on aluminum
-1/8" 2-flute Carbide end mill for use on aluminum

(source? McMaster has a wide selection, but a friend advised me against getting tools from them.)

I read a bit about smaller bits deflecting more, and since carbide is more rigid it won't have that problem as much.

Now I understand that the 2 flute end mills are better for aluminum because they allow for chips to clear better, but they leave a rougher finish. They also can "lift" on the part if it's not secured properly and can be more dangerous. Someone had suggested a 3 flute instead to alleviate these issues.

I've decided to go with the idea of mounting a toolmaker's vise to my compound rest and mount the compound rest to an angle plate. I have plenty of room and just need to work out the details now. One thing I am still unsure about is my method for moving axially on the lathe and how that will translate to the lathe-mill. Right now, I bring my carriage close to the part and lock it in place, then use the compound rest at 90 degrees to move axially on the part while using the cross slide to move radially. If I use my compound rest as the vertical slide, I will no longer have that precise adjustment and will have to use the carriage to move axially. I have found this doesn't work that well - it's a little rough feeling and I have no measurement unless I mounted a micrometer or dial indicator. Am I doing things wrong, or is this to be expected?


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## precisionworks (Jan 17, 2012)

> (source? McMaster has a wide selection, but a friend advised me against getting tools from them.)


McM has a very good selection of end mills & all I've gotten there are USA made, cost less than MSC & shipping was $5. Enco sales can be good IF the end mills are brand name (like the OSG they had on sale recently). EBay is always a possibility.

Carbide tooling is rigid & may or may not work for lathe milling - if you hear a sharp snap & see that one end mill has become two you'll want to switch to cobalt. I run 2/3/4 flute end mills in aluminum, either 1/16", 3/32" or 1/8" and cannot tell much diff ... but they spin at 50,000 rpm in the air spindle attached to the mill.



> I have no measurement unless I mounted a micrometer or dial indicator.


A mag-back indicator on the ways works well.


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## kuksul08 (Jan 17, 2012)

Yikes, 50,000RPM is smokin.


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## precisionworks (Jan 17, 2012)

kuksul08 said:


> Yikes, 50,000RPM is smokin.



It's about right for 6061T6 or 7075 aluminum:
1/16" end mill @ 800 sfpm
3/32" end mill @ 1200 sfpm
1/8" end mill @ 1600 sfpm

These are high shear (aluminum specific) tools. More speed is better up to around 2000 sfpm & they don't last long if run dry.


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## kuksul08 (Jan 17, 2012)

I didn't realize it needed to be so fast. Are these maximum ratings, or can you run at slower RPMs with low feed rates if you choose?


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## tylernt (Jan 17, 2012)

Milling on a lathe, it does become hard to control "Z" because your carriage usually has no dial. A few options:

Install a carriage DRO.

Mount a handwheel to the leadscrew and engage the halfnuts (disconnect the leadscrew from the geartrain!). For an 8TPI leadscrew, one turn of the handwheel moves "Z" 0.125". Beware there may be lots of backlash compared to what you're used to.

Use a dial indicator (as you already mentioned). You could probably mount it to the ways on the tailstock side of the carriage, that way you can leave it mounted while working.


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## precisionworks (Jan 17, 2012)

kuksul08 said:


> I didn't realize it needed to be so fast. Are these maximum ratings, or can you run at slower RPMs with low feed rates if you choose?


Yes you can but the inch/minute (meter/minute) feed has to be really slow. At 50K the cutter can be fed as fast as the wheel can be turned.


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## kuksul08 (Jan 17, 2012)

Good info. I actually have a single axis DRO - it's a Mitutoyo, but i don't have the encoder that goes to it, just the unit.

You can see it on top of the headstock here: 





The dial indicator I have is a 'Teclock" .001-1.00 which might work as well if I can just mount it to something.


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## precisionworks (Jan 18, 2012)

$18 at Penn Tool.


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## kuksul08 (Jan 18, 2012)

That's a great idea. I already have a hard drive magnet I can attach to my indicator.

Thanks everyone for the input. I will definitely post up photos and/or a DIY for this conversion once I get parts in.


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## kuksul08 (Jan 22, 2012)

Alright, I've been doing tons of research and I'm about to order the following: 

End Mills 
1/8" 3fl Atrax carbide with TiN coating - from Enco ~$6 
3/8" 3fl Atrax carbide with TiN coating - from Enco ~$15 
Hopefully these will be great for aluminum, plastic, and some steel. 

Angle Plate 
I measured my lathe and based on the cross slide and compound rest being in the middle of their range, an 8x8x8 angle plate would look like this. The 8" height and depth are good, but it would have 2.75" of overhang on the right side of the cross slide. I guess it doesn't matter. The only problem I'm having is with the mounting holes I will have to drill. They don't tell you where the ribs (or slots/holes on some pre-slotted versions) are located. It might be better to get one without ribs or holes if I can find it.





Vise 
I was going to get a precision toolmaker's vise, but there are a few problems. I have used 2 of them at work - one being a screw version and the other a screwless type. The screwed version is not bad, but could potentially have jaw lift and you can't put much torque in. The screwless type is a big hassle to work with. Also, mounting might be kind of difficult for me since they only have slots for T-nut clamps. For just a little bit more, I am looking at a "kurt replica" 3" milling vise. Swiveling base, removable jaws, no-lift mechanism. LittleMachineShop and Shars both offer them for less than $100 (ie http://littlemachineshop.com/products/product_view.php?ProductID=2500&category=1963256912). Enco has a nice looking 5" version but that's too big I think. 
You guys have any input on these replica vises? I'd consider the real Kurt brand but I don't see any small enough (3" jaw width). 

Oh, and Enco has a NCCJAN free shipping code if anyone is interested


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## precisionworks (Jan 22, 2012)

> The only problem I'm having is with the mounting holes I will have to drill. They don't tell you where the ribs (or slots/holes on some pre-slotted versions) are located.


The solid plates are best used for inspection while the slotted plates are much easier to set up for milling.


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## kuksul08 (Jan 23, 2012)

Well, I took the plunge. It's not cheap but will be worth it I hope. Just one question still.

How would you go about drilling a 1" diameter hole in cast iron?


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## precisionworks (Jan 23, 2012)

Depends on the equipment used to turn the drill & how well you can clamp down the part - either way no lube is used, run the drill dry & suck up the powder with a shop vac if one is handy. 

Surface speed can be anywhere from 50-100 sfpm (200 minimum-400 rpm max rpm). Spot the hole with either a spotting drill or a lathe center drill & feed the 1" twist drill with as much pressure as your machine will handle, keeping feed below stall out. On a hole this size - if you have enough machine driving the drill - going from spotter or center drill to 1" is easy enough. On a low power drill press you may need to go from spotter to 1/4", then 1/2", then 3/4" and finally the 1" drill.

Most cast drills easily as it's soft, around 20 Rockwell C.


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## kuksul08 (Jan 23, 2012)

Okay, thanks 

I'll let you know how everything pans out.


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## kuksul08 (Feb 5, 2012)

Success! I converted to a lathe-mill with a $70 vise, $80 angle plate, a couple steel plates and a few screws. Totally worth it for the work I will be doing. Thank you all for the advice and helping me get this working.








Using a 3/8" 3fl TiN coated carbide end mill. The 3-jaw chuck seems to work, but I have a collet closer so I might get some collets.






I had to make this plate to fit in the compound rest. I used two 5/16" steel plates and JB welded them together rather than machining grooves in them. 20 minutes with the sander afterward and it fits perfectly.






I had my machinist friend drill these holes in the 8x8x8 angle plate. I only have two T-nut type things for now, but I made more (see below)






My first milling project - putting a couple flats on these nuts.






Lastly I had to replace my carriage lock lever with a nut because the angle plate would hit it.







I need to square it up perfectly still. I am going to make some stops on the angle plate so it is easy to square up each time I switch between lathing and milling.


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## BVH (Feb 5, 2012)

That really looks fantastic!


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## precisionworks (Feb 5, 2012)

Nice job  And you did it without breaking the bank.


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## kuksul08 (Feb 6, 2012)

Thanks  I'm so glad it worked.

I was worried about the overhanging weight putting a lot of stress on the cross slide and binding it up. It turns out that it's almost balanced as is, since the plate overhangs so much on the right side. If I were to remove the swivel base from the vise, it would stand on its own without putting any torque on the cross slide.


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## tylernt (Feb 6, 2012)

Removing the swivel on the vice, even on a real mill, is a good idea. Less opportunity for chatter.


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## gadget_lover (Feb 6, 2012)

tylernt said:


> Removing the swivel on the vice, even on a real mill, is a good idea. Less opportunity for chatter.



In this particular case, the swivel provides an axis of setup that he does not otherwise have. On a mill the vise can be bolted down in many orientations. With this mount it only goes one way. It will make it easier to tram the vise, for instance.

Daniel


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## precisionworks (Feb 6, 2012)

> In this particular case, the swivel provides an axis of setup that he does not otherwise have.


+1

For lathe milling the swivel will be valuable.


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## gadget_lover (Feb 6, 2012)

It has probably been mentioned here, but I'll say it again since you mentioned that the 3 jaw was doing OK.

The end-mill is hardened, and so are the jaws of your chuck. This gives you a poor over all grip on the end-mill shank. I think it has to do with the idea that the points of contact will be very small. If you use a collet the metal will conform to the harder end-mill and give you more surface area and therefore a better grip.

An end mill holder does not rely on the distortion of the metal. The end mill holder has a tight fitting hole and uses a set screw from the side to prevent any up / down movement or rotation.

A normal collet will work if clean and tight. 

Daniel


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## kuksul08 (Feb 6, 2012)

I see. I have read about the end mills 'walking' in or out in the jaws, which is definitely not good for anything.

Since I have the collet closer already, I guess what I need is a collet chuck and a few collets. I can't remember what style they are, but the name 5C comes to mind.


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## darkzero (Feb 6, 2012)

kuksul08 said:


> Since I have the collet closer already, I guess what I need is a collet chuck and a few collets. I can't remember what style they are, but the name 5C comes to mind.



Since you have a collet closer, you wouldn't need a collet chuck. What you need is a collet nose adapter. You would remove the chuck & insert the 5C nose adapter into the spindle's taper. The collect closer would screw into the the back of the spindle, the collect closer lever would mount on a bracket, & the collect would screw into the end of the collect closer. You would adjust the tension of the collet on the collet closer then pull on the lever to "close" the collet.

Check around, you might even have the nose adapter somewhere. It would look similar to this: http://www.tools4cheap.net/prodimages/3atadapter.jpg

If you don't have it, assuming your spindle's taper is MT5, you can get the MT5 to 5C adapter from Grizzly for about $30. The p/n is P4026001. It's a replacement part so you would have to call to order it. Not sure if it comes with the pin (p/n P4026047) so be sure to ask if you order it since you will need that too. http://cdn0.grizzly.com/partslists/g4026_pl.pdf


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## KC2IXE (Feb 6, 2012)

precisionworks said:


> ....snip... On a hole this size - if you have enough machine driving the drill - going from spotter or center drill to 1" is easy enough....snip....



Hehe - made me think of the job where I first ran a lathe and mill. We were a smallish fab shop, and MOST holes we mader were punched (Yes folks, you can punch BIG holes in I-beams with the right tools). When the stock got thicker than the hole however, we drilled. I can remember drilling BIG 1" - 2" holes in plate steel. We had a fairly good sized "Buffalo" drill press. When I say "good sized" I'm talking MT5. A 1" hole typically would get centerpunched, and just drilled straight through. Amazing what 15-20HP on a nice rigid machine, turning slowly (like 80-90 rpm) with power feed can drill

That said, if I had to drill a 1" hole today on a regular basis, I'd look at an annular drill


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## kuksul08 (Feb 6, 2012)

Oh you know what, I think I have that part already. So all I need is a 5C collet and it should work!
Thanks :wave:


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## StrikerDown (Feb 8, 2012)

I didn't see this mentioned, if it has been please disregard.

Besides the grip of a 3 jaw being iffy at best the 3 jaw typically has considerable run out. If the run out is bad enough you will be cutting with only the high side of the end mill and this will cause excess wear of the end mill as well as affecting your surface finish. The less run out the better all around and typically the collet is much less. 

I wish I had a collett closer, My PM 1440 was advertised as coming with a "Collet Closer" but it arrived with a cheap Chinese collet chuck, I called the vendor and his response was the chuck closes collets so it's a collet closer!

Nice job on the milling adapter!


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## darkzero (Feb 8, 2012)

StrikerDown said:


> I called the vendor and his response was the chuck closes collets so it's a collet closer!


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## kuksul08 (Feb 8, 2012)

Thanks ^^ Don't you hate false advertising? The collet closer doesn't seem like much, just a long shaft with an enormous bearing at one end.


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## precisionworks (Feb 8, 2012)

> I wish I had a collet closer,



Start with 5C coffee grinder (spin index):






Pull spindle out:






Add an extension to the draw bar:






Make the extension the length of the headstock tube. Photo shows my 5C collet chuck used with a super spacer but it's no more trouble to make one for a lathe:






Light gripped in 5C collet & set up for trit slots. Rubber boot & switch have to be removed & the tailstock brought up but it's ready to work. I use it for just about every trit slotting job. It does help if your chuck runs dead nuts or if your chuck is a Set-Tru (this one is):






Total cost (if you already have the spin index) is $5 in materials. Time to machine extension is about one hour.


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## StrikerDown (Feb 8, 2012)

Barry I'm looking to have the 5C at the Spindle behind the 4 jaw. Or just the 5C alone to turn stock in... I can do that with the collet chuck but the TIR of my Chinese C chuck is not the best... When in the spindle in the optimum of three possible positions it's only slightly better than the cheap Chinese 3 jaw, In the other two positions it is horrible.


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## precisionworks (Feb 9, 2012)

> the TIR of my Chinese C chuck is not the best...


Got a 4-jaw? The worst 4-jaw in the world will adjust out & run as true as the finest 3-jaw Set-Tru.

Forgot to mention I point that's important ... the diameter of the 5C spindle isn't small. It easily slides through the 8" chuck on the super spacer because of the large bore. Probably will not go through anything under 8".


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## kuksul08 (Feb 14, 2012)

Two more questions:
-How do you measure this TIR? Do you simply spin the chuck slowly with a dial indicator on the OD to see if it changes at all?
-I was doing some cutting with my 3fl end mill in 6061 aluminum. I was about D/4 deep on my 3/8", running pretty fast (I cant remember, but IIRC it was over 1000RPM), and feeding very slowly by hand. The surface finish at the end of the end mill was perfectly shiny and smooth, but along the sides were very rough looking. Is this to be expected with a 3fl, or was I doing something wrong? I didn't notice significant vibration or chatter. I was not climb milling.


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## gadget_lover (Feb 15, 2012)

The speed that you run the mill at depends on the size of the mill as well as the material that you are cutting. 

The finish that you get from the sides sounds like either you have chatter, runnout or you are simply feeding it too fast. Chatter can come from the part moving. It can also come from the mill sticking out too far.

Daniel


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## kuksul08 (Feb 16, 2012)

Thanks Daniel.

I looked into the speeds a bit more.

According to N=4V/D, I should have been running 4(300SFPM for aluminum)/(3/8" end mill) or 3200RPM. My lathe maxes out at 1350RPM, so the best I can do is lower my feed accordingly.

I'm going to order some collets to eliminate the runout possibility. Chatter could very well be happening, although I don't know how I'd know. It is pretty quiet, I tightened the gibs, and always lock any axis not in use.


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## precisionworks (Feb 16, 2012)

Are you running an end mill designed for aluminum? They work very well while most GP (general purpose) tools work poorly. Try switching to one of those & your results should improve dramatically - if not it will tell you that more adjusting is necessary on the lathe. 

MoldmakingTechnology article.


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## gadget_lover (Feb 16, 2012)

kuksul08 said:


> According to N=4V/D, I should have been running 4(300SFPM for aluminum)/(3/8" end mill) or 3200RPM



It's usually OK to run a bit slower, just harder on the tools and takes longer. The 300 SFPM is to maximize production.

A 3/8 inch end mill will not stick out of the collet very far before it starts to vibrate (chatter). 

Chip removal is important to a good finish. A 3 flute should leave plenty of room for chips. What lube were you using? That will also impact the finish.

Daniel


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## kuksul08 (Feb 16, 2012)

I was not using an end mill designed specifically for aluminum - just a 3 flute solid carbide. It was sticking out about 1.5" I'd say from the chuck, which was as deep as I could go before the flutes started. I tried both using no lubricant, and then using some RapidTap cutting fluid. The RapidTap made it smoother, but the chips didn't evacuate. They just sat there on the cutter or beside the cut, it's probably far too high of a viscosity.

I have ordered a larger (3/4") high speed steel, 2 flute, high helix (AL specific) end mill and I will try using WD-40 and maybe an air nozzle if I can keep the mess down. Hopefully this will help.


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