# suggestion for upgrade to my mini mill



## gt40 (Dec 2, 2011)

I have had a mini mill for a year with dro. I am wanting something more rigid and more capability that maybe is worth doing cnc on. Any suggestions would be appreciated.


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## gt40 (Dec 6, 2011)

After reading a bit more, I am thinking of a mill drill like the rf31 or rf45. Is the rf45 worth the expense for flashlights compared to the 31?


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## Th232 (Dec 7, 2011)

From what I read when I was making the same decision, the dovetail column on the RF-45 means you can raise and lower it while keeping the head in the same position, the round column on the RF-31 means that it'll move, so if you do one operation then realise you need to raise/lower the head (changing tools?) then you could be in for some real fun. A round column will also be less stable(?). I had bookmarked a site where someone had converted a RF-45 to CNC, but I can't seem to find it now.

Bear in mind, is flashlights really the *only* thing you'll be doing with this mill? I know some here might, but it feels to me like buying a car only to carry the weekend groceries, when it could be doing so much more, especially if you go ahead and CNC it.


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## precisionworks (Dec 7, 2011)

> if you do one operation then realise you need to raise/lower the head (changing tools?) then you could be in for some real fun.


Re centering the part after raising/lowering the head is pretty easy ...

1) Use an Indicol clamp to attach a dial test indicator to the spindle. Swing the DTI tip around the part while adjusting X-Y position of the part so the needle does not move.

2) Use a Blake Co-Axial indicator.

3) Use a laser center finder like Will Q.

4) Use an optical centering scope. 

5) To pick up only one edge (versus center of a part) an edge finder works well.

Probably a few other methods and all take only a minute or two.


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## Maglin (Dec 7, 2011)

I'm doing a conversion on a RF45. With all the money that you will have to put into the conversion and all the time involved you will spend less on the mill than everything else by far. Most people that convert a RF31 end up going to a RF45 or IH mill. The issues with the very limited quill travel which is about 4" really limits stuff like drilling and boring on the mill without having to raise the head and then you have to realign it with like a indicating hole that you have just to realign the centerline of the spindle with where the machine controller thinks it is.

I paid $2K for my RF45 and a IH is about $3K. I have over $3K in electronics, ballscrews, and material for the conversion and I still have a lot of time in labor to go before it's all finished. Check out cnczone.com and their is a large wealth of information. If you have a lathe already you could maybe machine your own ballscrews and thread your own ball nut mounts, but if you don't you could be looking at another $300 in added costs for the machine work on the screws and the large taps for the ball nuts.


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## Maglin (Dec 7, 2011)

Oh and about something you said in your second post. You are getting a bigger mill just for flashlights. I guarantee that if you get a far more rigid mill like the RF45 under CNC you will end up doing far more than flashlight stuff. Your current mini mill is a toy compared to even the RF31. If CNC is just a passing thought I would look around for a good used Bridgeport or BP Clone in good shape. You can find Dovetail Column J-Headed Bridgeports for 2500-3000 and they are very nice machines with usually a 1.5-3HP 3PH motor on them. I have a 1943 M-Head round column BP and it is far more rigid than the RF45 but only has a 1/2HP 3PH motor on it and I usually stall the spindle with .3" DOC with .5" cutters feeding what I think is really slow. Just something to think about. I wanted the BP just for a manual mill to do work on my RF45 and all the round column J-heads where going for $2+K so I found this one with power feed on the X for $900 and it's in ok shape.

So Decide on what you want and if you can wait you can find some decent machines used but you usually have to wait. Also you can check with all your local machine shops if they have any machines they are wanting to sale or know where some are for sale. Talk to the owners and not just the workers. I notice at least around here most of the workers are just cheap labor and that is coming from the actually owners who are machinist with over 40 years of experience.


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## gt40 (Dec 9, 2011)

Thanks very much for the info. I need to think about this a bit more.


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## PEU (Dec 10, 2011)

If you do not have the patience/time/knowledge to retrofit a manual mill to CNC why not purchase a ready made one? I sell Syil machines here in Argentina, and for the money they are a very good deal, 2011 models saw very nice improvements in the spindle. Depending on the accuracy you need you could go with the X4 or X5 models, being the X5 more accurate. If you want bigger machines there are more models available. Check with the US distributor www.syil.ca, his name is Keith.


Pablo


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## gt40 (Dec 14, 2011)

Thanks PEU for the suggestion. I think I want to go through the process of actually retrofitting for cost and my own knowledge. 

On a different note, I am now leaning on a *PM-30LV 

*Link:
*http://www.machinetoolonline.com/PM-MV-BenchMills.html

*Looks to be in between an rf 45 and bv20 style and is square column. Would this be a decent candidate?
* *


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## precisionworks (Dec 14, 2011)

I've never run a RF45 or a PM-30LV but I would not think that either one would be any more rigid than my RF31. It seems that many people buy the square column machine because they aren't sure how to pick up location after raising or lowering the round column head. Since locating holes, features & edges is something a machinist has to do until his heart stops beating it is worth the time to learn that skill.

I can't say how much time I've spent running J-head Bridgeports but it is certainly hundreds of hours and likely more than that. IMO the RF31 is comparable to a J-head in all respects except that the RF31 lacks a knee movement. The same DOC & feed can be used on the RF31 as on a J-head. The RF45 & PM-30LV should be comparable.


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## StrikerDown (Dec 14, 2011)

I have a Rong Fu, RF-31 and while I agree with what Barry has said. If I were buying my first mill again and Knew what I know now I would go with a Knee mill, something like this: http://www.machinetoolonline.com/PMx7550Mill.html at a minimum if money were an issue. If not I would go with a somewhat larger table size, but either machine would come equipped with 3 axis DRO! The only Advantage I have found with my RF-31 is that if I need to mill on the end of a long object the head can be swung to the side and the object clamped to the table with it's length hanging down the side of the table and stand, but this is rather limited in application. Keep in mind I am not planning planning on a CNC conversion though, can't help with that!


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## precisionworks (Dec 14, 2011)

> If I were buying my first mill again and Knew what I know now I would go with a Knee mill, something like this: http://www.machinetoolonline.com/PMx7550Mill.html at a minimum


+1

Any knee mill is much easier to set up & use than any mill drill. That's money well spent.


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## gadget_lover (Dec 14, 2011)

The only downside to that mill is that there is no ram. (moves head in and out) That restricts your work envelope to the travel of the table.

Mine has a similar limitation, and several times I have set up a piece only to find that I can't get to edge furthest from the column because the workpiece is against the column. The 'distance from spindle to column' becomes important.  That is not listed on the PMx7550 mill.

Dan


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## PEU (Dec 15, 2011)

of your two choices I would go with the RF45 as it looks sturdier/heavier, the 30LV column is too tall too thin IMHO. http://www.hossmachine.info/RF-45_Clone.html


Pablo


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## precisionworks (Dec 15, 2011)

> I would go with the RF45 as it looks sturdier/heavier, the 30LV column is too tall too thin


+1

The 30LV weighs 484# while the RF45 weighs 800#. Big difference.


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## gt40 (Dec 30, 2011)

precisionworks said:


> +1
> 
> The 30LV weighs 484# while the RF45 weighs 800#. Big difference.



Thanks for the input. I think you are right about the 30lv after seeing this:
http://www.youtube.com/watch?v=X_6i4SN05HU

Anyway, I talked to Matt at Precision Mathews and he said the smaller mills are just not the same as the rf45 types for rigidity. He then went on to tell me they had a variable speed all set up in stock. I pulled the trigger after he reeled me in with with an upgraded 3hp variable speed motor and drive factory setup and a nice discount + shipping with liftgate. It apparently has a different gear box and gears with just low, medium and high gear setting + the variable rheostat and a tach on it. He says this setup is 50 to 3000 rpm which is higher than regular rf45 clones. It is supposedly a lot quieter too. 

Now I have to wait for it to ship across the country as I am in Santa Monica. This machining hobby is going to ruin my wallet!

Happy New Year


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## precisionworks (Dec 30, 2011)

Congratulations :goodjob:

You'll love the lowest speed for turning a 2" hole saw through steel plate & the top end is about right for small end mills in Ti or SS.


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## StrikerDown (Jan 1, 2012)

Congratulations!  Don't forget the Pictures... In other words charge the camera now! 

About your wallet... You have no idea! :sick2: :devil:


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## precisionworks (Jan 1, 2012)

> charge the camera now!
> 
> About your wallet... You have no idea!


There is an absolute inverse relationship between machine tool photos & bank account balance ...


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## cmacclel (Jan 1, 2012)

30lv Only has 2.5" of quill travel???? if so.........that really stinks. I have about double that on my RF31.

Mac


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## gadget_lover (Jan 1, 2012)

I figure that the 2.5 quill travel added to the amount that the head travels greatly increases the effective plunge in one setup. That's the big advantage of square column over round, isn't it? Of course, the RF31 has more reach with the same tool... There are advantages to every setup and design.

Dan


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## wquiles (Jan 2, 2012)

Congrats on your new mill - please post new photos when you get it 

Will


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## gt40 (Jan 3, 2012)

I just spoke to Matt at Precision and he confirmed it was shipped. I hope the dc motor and variable speed option is worth it but I am relying on his advice on this. He says it comes with less gears- high, med, low and is quieter than the regular rf45 type machines + the variable speed controller is factory wired and mounted on the machine.

Pics to come...


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## wquiles (Jan 3, 2012)

gt40 said:


> Pics to come...



All right


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## StrikerDown (Jan 4, 2012)

Speed control at the twist of a dial is sweeeet! It's the only (yes ONLY) thing I miss about my 7x10 lathe! 

On my RF-31 I would jump on a VFD for the variable speed in a heart beat if I didn't want a bigger mill! Since the space is at a premium a VFD might be in the future... It looks like a fun project! :naughty:


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## gt40 (Jan 4, 2012)

I ordered the mill just before new years and Matt at Precision gave me a great deal: figured at 400 bucks more than the stripped mill, factory vfd with a 3hp upgraded motor seemed worth it vs diy variable speed. 

He said it is on the way and I should get it monday or tuesday.

On another note, found a good deal on a kurt 688 vice for $450: http://www.ritchieindustrialsales.com/kurtvised688onsale45000.aspx

This will be my first "real" vice. I can't wait...


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## wquiles (Jan 5, 2012)

gt40 said:


> On another note, found a good deal on a kurt 688 vice for $450: http://www.ritchieindustrialsales.com/kurtvised688onsale45000.aspx
> 
> This will be my first "real" vice. I can't wait...



It might not be the same exact/identical mode, but if you wait for the free shipping from ENCO, you can get the Kurt 6" vise for $420 shipped 

That being said, if doing it all over again, I would have gotten the Premium 6" from Glacern Machine Tools instead:
http://www.glacern.com/gpv_615

Will


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## gt40 (Jan 5, 2012)

wquiles said:


> It might not be the same exact/identical mode, but if you wait for the free shipping from ENCO, you can get the Kurt 6" vise for $420 shipped
> 
> That being said, if doing it all over again, I would have gotten the Premium 6" from Glacern Machine Tools instead:
> http://www.glacern.com/gpv_615
> ...



I almost pulled the trigger on the GPV 615. The Kurt has a 8.8" max jaw opening though vs 6.25" for the Glacern. In fairness, the GPV is 1.9" shorter overall length so maybe I will regret the Kurt sticking out a bit more but I figure you can never have too much jaw capacity. The 688 is more like their regular model gsv690- It is 19.25" overall length with 8.95" max jaw opening. It is also $50 bucks cheaper than the Kurt. I am not going production cnc and stacking vices on the table just yet so my newbie logic chose the greater capacity.

Will, why you would do the Glacern over the Kurt other than price?


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## wquiles (Jan 5, 2012)

gt40 said:


> Will, why you would do the Glacern over the Kurt other than price?


It is not about price. I like the dual mounting holes on the premium Glacern, the fact that the back/fixed part of the vise is a continuous piece (unlike the regular/Kurt vices where the fixed part is a second piece), plus I like how the premium Glacern unit can be mounted on its side - it just overall looks like a better buy, more rigid, and more flexible mounting options. I already got a few parts from Glacern and their quality/finish is simply superb!


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## precisionworks (Jan 5, 2012)

If the Glacern were $200 less than a comparable Kurt it would be a great buy. Even though the vises are ground in the USA they are cast in (some unknown foundry) in Asia. That isn't to say that nothing good is cast in Asia, but the best castings in the world - today - are from Europe, Japan & the USA. 

Since the bottom of the vise has to be wiped clean every time the vise is mounted on the mill would you rather see "Made in USA with imported parts" or would you prefer to see this:


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## cmacclel (Jan 5, 2012)

Barry your a riot! Did you really un-mount your vise and flip it over to post in this thread 

Mac


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## cmacclel (Jan 5, 2012)

I have and like this vise

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=9200809&PMAKA=308-0101

Get it with the 20% off and free shipping the price can't be beat at $300 shipped.


6" wide 9" opening


I also have a Kurt D688 and like the Parlec better.

Mac


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## StrikerDown (Jan 5, 2012)

USA!!!:





Picked up my D675 for someting like $205. plus shipping ($90) NIB on ebay.

No regrets... It has done everything I ask, Very Well!


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## precisionworks (Jan 5, 2012)

> Did you really un-mount your vise and flip it over to post in this thread


No, the Kurt usually sits on the bench as the super spacer & tail stock take all the available room on the mill table. For small jobs the tail stock comes off easily & the Kurt goes back on the right side of the table. When my lottery numbers come up I plan to buy a second mill


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## cmacclel (Jan 5, 2012)

precisionworks said:


> No, the Kurt usually sits on the bench as the super spacer & tail stock take all the available room on the mill table. For small jobs the tail stock comes off easily & the Kurt goes back on the right side of the table. When my lottery numbers come up I plan to buy a second mill



Exactly as mine stays setup 99% of the time. I have a Horizontal / Vertical 6" rotary table with Bison 3-Jaw that stays on my RF31. My big Wells mill has the 688 mounted on it but only gets fired up maybe once every couple months. I did just buy a monster of a vise. A Gibraltar 6" Swivel / Rotary vise. It's weighs in at almost 100lbs! I put in a 150$ offer on Ebay and they accepted with free shipping


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## gt40 (Jan 12, 2012)

It arrived. I rented a hoist and came home a bit early to get it in the garage. No major issues from shipping and the factory variable speed control looks cool:





















I will hook up power and figure a bit more tomorrow. I also get to clean the garage as I had to move everything to get the hoist into the garage


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## StrikerDown (Jan 12, 2012)

Very Cool, Congratulations!!!:naughty:

If you are average height or taller you might want to raise the base up 4-6" to help save on back fatigue... Bending over for long periods of time real pain!

Here is how I did mine:
















Whlie leveling isn't too critical on a mill like it is on a lathe, my garage floor has a slope to let any possible water run out the door so the feet let me get it close to level so those round parts don't run for the door also!


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## precisionworks (Jan 12, 2012)

> you might want to raise the base up 4-6" to help save on back fatigue...


+1





















Material for the floor base & for the riser above the stand is 2" square tube with 1/4" wall thickness.


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## wquiles (Jan 12, 2012)

gt40 said:


> It arrived. I rented a hoist and came home a bit early to get it in the garage. No major issues from shipping and the factory variable speed control looks cool:
> 
> (snip pics)
> 
> I will hook up power and figure a bit more tomorrow. I also get to clean the garage as I had to move everything to get the hoist into the garage



Congrats - that looks like a great machine you got there


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## gt40 (Jan 12, 2012)

I got the mill wired and also got the Kurt vice. All in all it works great although I am going to call PM about what passes for a draw bar:






Basically a long double sided bolt with a couple of nuts on the end. The real issue is it doesn't center and is too long so it just spins in a lopsided way.

On another note, whoever took the time to tram the mill at the factory should be given a raise. I took various measurements all over the table with my mitsumoto dial indicator after zeroing it was dead flat at .0000 on all 4 corners. I am now officially scared to move it, touch it or do anything to disturb the tram 







Finally, shot of the Kurt:


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## gt40 (Jan 15, 2012)

Well, I decided to just make a new stand. I had some scrap 4" diameter tubing that was 1/4" thick. Picked up some 2" diameter/ 1/4" thick tube for cross members + found a 1/4" thick plate at at industrial metal supply that was 25x36" in the rems stack. I cut it down to 25" x 30". Finally, I added some overbuilt casters with retractable legs(2500 lb rating!) and ended up with this:







Side by side with the old stand. You can also see where I drilled on the wrong side. Fyi, the mill just drilled through 1/4" thick steel with a 2" hole saw like it wasn't there:






Caster:






I climbed up on on it with both the mill and me up on the table and it is solid.


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## StrikerDown (Jan 15, 2012)

Awesome job! I love the casters.


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## STR (Jan 16, 2012)

gt40 said:


> I have had a mini mill for a year with dro. I am wanting something more rigid and more capability that maybe is worth doing cnc on. Any suggestions would be appreciated.




I have the Harbor Freight mini mill that I installed the belt drive conversion on. Its pretty much a great machine and much less noisy since doing that and I got into it for about $625 plus or minus after doing that. While my set up works and I find it adequate I would buy the Sherline if I had to do it again. I could have gotten into one of these for just a few bucks more really at least at the time when I bought my mill that I use. I believe my Harbor Freight model is the 44991 if I'm not mistaken which runs about $600 before you even add the belt drive and the belt drive is an additional $220 plus you have to install it so I'd seriously look at the Sherline made in the USA units since you are pretty much talking the same money. The Sherlines don't take up near the foot print in your shop anyway and they are quality machines built to last.


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## precisionworks (Jan 16, 2012)

Nice job on the stand 



> got the Kurt vice.



Mounting the Kurt like that puts a lot of stress on the T-slots as there's quite a bit of leverage working on the T-bolts. You may want to make a simple sub base that allows bolting up on the T-slots closest to the column.


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## gadget_lover (Jan 16, 2012)

STR said:


> I have the Harbor Freight mini mill that I installed the belt drive conversion on. Its pretty much a great machine and much less noisy since doing that and I got into it for about $625 plus or minus after doing that. While my set up works and I find it adequate I would buy the Sherline if I had to do it again.



I think the Sherline is more comparable to the smaller HF unit, the Micro Mill. The mini mill has about 80% more of everything... power, weight and travel in the X,Y and Z directions. The biggest Sherline would be a big step down.

Daniel


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## BVH (Jan 16, 2012)

I'm certainly no structural engineer so take this question as it is, an honest question. IIRC the the machine weighs about 950 plus the weight of the VFD, vise and the work so probably approaching 1100 pounds. I am not able to see if there is a cross member on the underside of the 1/4 plate. If not, it just seems like there would be some flexing of the 1/4" plate due to the dead weight and dynamic load induced weight?


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## gadget_lover (Jan 16, 2012)

The problem appears to be that the weight of the mill (and some miling forces) is supported by the inboard lip of the t-slot. I can see where that might be sub optimal since it is a fairly small cross-section. 

Can that lip around the base be used for clamping? If so, then you could offset the forces by putting a clamp in the second t-slot and clamp the vise nearer to the column. hat's a lot further away from the edge of the table that is acting as a fulcrum. 

Daniel


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## gt40 (Jan 16, 2012)

BVH said:


> I'm certainly no structural engineer so take this question as it is, an honest question. IIRC the the machine weighs about 950 plus the weight of the VFD, vise and the work so probably approaching 1100 pounds. I am not able to see if there is a cross member on the underside of the 1/4 plate. If not, it just seems like there would be some flexing of the 1/4" plate due to the dead weight and dynamic load induced weight?



The frame is actually extremely rigid. I literally climbed up on the mill with the vice on it and climbed around to gauge how stiff things were. I was going to put a cross frame on it but it is bomb proof. Keep in mind the base is bolted to the 1/4" plate and there isn't much overhang. The 4" diameter beams are welded directly to the plate supporting the 4 corners of the mill. They were previously structural supports holding the back of my 2 story house up. The stock base that came with the mill creaked when I put the mill on it in comparison. Basically the (4) 4" diameter 1/4" thick tubes are doing most of the work

To give you an idea, here is a pic of the pizza oven I built this summer. It is over 6,000 pounds of masonary with over 500 heavy fire bricks in the build + a 7" concrete foundation I poured on it . Then I framed it and covered it with stone vineer and it is also 4" square tube that is 1/4" thick:






Here is the steel frame covered with a few more thousand pounds of framing and stone veneer all finished:






As far as the vice, took everyones advice and found that by shortening the lock nut on the front wheel, I could crank it more and gain an 2" of travel. this allows me to move the vice to the middle track for mounting and it balances on the table under its own weight:






I changed the mystery brown stuff passing for oil in the gear box with mobil DTE:






Thanks everyone for the suggestions. After a year and a half of jumping into trying to learn how to machine things and make my own lights, I am still figuring things out and grateful for the help. This place is awesome for the info and advice. I must say I was distracted by the pizza oven build this summer and it is good to be back.


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## themayor (Jan 28, 2012)

what are the slots in the bottom of the vise for?


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## precisionworks (Jan 28, 2012)

> what are the slots in the bottom of the vise


Most mill table tooling (vice, indexer, super spacer, tail stock, etc.) comes with locating keys or tongues so the vise can be quickly aligned parallel to the direction of travel. Some people love them & use them but mine go to the recycler  Two reasons for this:

1) The tooling has to be lifted high enough to clear the key & then gently lowered so the key engages the slot. Hard to do with a 70# (32 Kgs) Kurt vise & impossible with a 165# (75 Kgs) Super Spacer.

2) Unless lots of time is taken to precisely fit the key to the slot the alignment is suspect. It takes about a minute for me align the Kurt using an Interapid indicator & I know it's within .001" across the 6" face.


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## themayor (Jan 28, 2012)

ok got ya kinda what i thought it was for


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## KC2IXE (Jan 28, 2012)

precisionworks said:


> 2) Unless lots of time is taken to precisely fit the key to the slot the alignment is suspect. It takes about a minute for me align the Kurt using an Interapid indicator & I know it's within .001" across the 6" face.



I never use them either, BUT fitting them isn't that hard. If you do a lot of swapping of the vise on and off, it pays. I tend NOT to mount my vise centered, but way to one side (say 1/4 the way), so I can use the OTHER side of the table without pulling the vise. There are some theoretical issues with table sag doing it that way, but I figure the other issue of evening out the wear of the ways over more area tends to balance it out


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