# SF M6 tailcup, version 2 ...



## wquiles (Apr 23, 2006)

As Andrew posted tonight, I just finished the second prototype of the tailcup for the SF M6 to use with protected cells. This was another good learning experience since I decided to try all operations from one side only. It went mostly good, but I still have tons to learn 

Here is the side facing the batteries (work still in progress):






(of course, a shot in motion!!!)






Here I am drilling the small hole through (blind), which ended up being a tad larger, but still good enough for a working prototype:






Since my tailend has some play, this is how I "fix" mine in order to have a steady drilling operation:






Here I am done with the battery side and I started work on the button side:











Of course, I lost some time since my pot/switch died!. Lucklily for me, the past owner send along TWO replacement parts, so I used one to get the machine operational again:






I am almost done with button side. Here I am making the grove on the back using the cutout blade:
















And here I am done and just cutting the part to length:






however, I got some point where I could not cut any longer, and it was not due to interference. It as almost as if the part got "work hardened" and would not bite any more 






so as you can see here, I had to finish it off by hand, with a hacksaw!, which I then had to sand and polish. Any ideas as to why this happen? What can I do different next time?:






here is the finished part in the middle, with a late model M6 cup on top and a very old M6 tailcup on the bottom:






One of the things that took a LONG time was to reduce the diameter of the taicup on the switch side. Since all tools that I have are "pointy", you are taking a very small amount of metal on each pass. Also, I had to cut the section far wider to allow for the actual cutting tool to slide-in and cut left-to-right. I even tried (for a little bit) to use the actual cutting tool on a side-to-side motion, but as you can imagine it is not strong/stiff enough to do this anyway. I made my own "narow" cutter to try to speed up the operation, but being just HSS it can't cut as fast as the tools that use the carbide inserts. Is there a better way to do this?

Will


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## andrewwynn (Apr 24, 2006)

really neat to see the pictures of the progress.. fun to have a 'real world' application to learn machining, huh? 

-awr


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## wquiles (Apr 24, 2006)

Yes, learning with a clear goal is more fun. Having the lathe is not exciting if you don't have some cool projects in mind. My problem now-a-days (with two small children) is not lack of projects, but lack of time to work on all of the projects I have in plans/started  

Will


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## gadget_lover (Apr 24, 2006)

Dang! I'm on a dial-up so the pictures take f-o-r-e-v-e-r to view. Looks like real nice work!


I've found that when parting, the tool can stop cutting partway through if it's either dulled or if it's not right at centerline. Yes, it can get work hardened too, but that's not a frequent occurance if everything is set right. Eyeballing centerline is not quite good enough.

I set mine to height by using the 6 inch steel rule trapped between the tip of the tool and the side of the turned piece. If the rule is not straight up and down the tip is not at the right height.

I use a diamond grit emory board from the drug store to clean up the cutting edge of the parting tool while it's mounted.




> Since all tools that I have are "pointy", you are taking a very small amount of metal on each pass.



The ones in the pictures appear to be 1/32 radius tips, not as pointy as some. They should be able to take out .025 to .050 at a pass. I find it's helpful to use a carriage stop on each side of the carriage when doing that kind of work to limit the carriage travel left and right. Then you can zip left-right and back very quickly. You've already discovered that the width of a cut while reducing the diameter has to include room for the tool itself.

My first carriage stop was a piece of 1/8 thick aluminum clamped to the BACK of the ways with a small C-clamp. It did not have to be real tight to stop the movement of the carriage.

You can use the parting tool as a grooving tool and as a cutter, but it's really designed to go straight in. I've used it as a cutting tool (moving side to side) when doing very light cuts in very narrow spots. I'm sure accuracy suffers.

You are doing well Will. Glad to see that pot did not delay you too much.

Daniel


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## HarryN (Apr 24, 2006)

Nice work Will. I am not sure about your particular material, but only a few Al alloys work harden - what are you using ?

It is also possible ( and I am just speculating here) that the heating from machining has essentially removed the original temper, and it is now very soft, almost copper like. Gadget Lover and I had quite a time machining off a thin disc of copper from a narrow dia. rod - partly because it would distort away from the cutter, and partly we had to switch to a different cutter specifically designed for cutting copper / brass. 

Daniel would have more details.


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## andrewwynn (Apr 24, 2006)

looking at the pictures it does seem like the parting tool is higher than the centerline, which would seem to me, that once you got far enough in the rounded part would actually be hitting the the 'chin' of the cutting tool and no longer the cutting edge. could just be an illustion, hard to tell from a 2D picture in a 3D world, but that makes total sense.


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## cmacclel (Apr 24, 2006)

Looks like the parting tool is to high. It's fine when the diameter is larger but the smaller it gets the cutting edge gets higher and higher until it no longer cuts. If it's tool low it gets bad real bad as the tool goes under the parts and something usually breaks!

As Gadget said and easy way to assure your toolbit is on the centerline is to take a 6" steel rule and sandwich the rule between the bit cutting surface and the part. If the rule is not straight up and down (vertically) adjust the height of your tool bit.


Mac


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## scott.cr (Apr 24, 2006)

In addition to being on center, the parting tool has to be exactly perpendicular to the workpiece. (I use a thread gauge to line mine up, but you could probably line it against a face cut too.)


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## wquiles (Apr 24, 2006)

I think that all of you guys are spot-on: the cutting tool was above the centerline which explains the problem I was having. I will try the "trick" with the straight rule next time to make sure that the tool is right 

Thanks so much guys 

Will


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## cmacclel (Apr 24, 2006)

wquiles said:


> I think that all of you guys are spot-on: the cutting tool was above the centerline which explains the problem I was having. I will try the "trick" with the straight rule next time to make sure that the tool is right
> 
> Thanks so much guys
> 
> Will




Above centerline Ok no problemo just re-adjust. Below the centerline be prepared to dodge the part when it comes out of the chuck 


Mac


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## olephart (Apr 25, 2006)

No doubt that it will act like that when it's above center. Looks like you extended the tool.

When ya do that it gets higher due to the angle that it's held in the tool. Whenever you make it stick out further, ya gotta re-center it.

It's less critical if you retract it, but it still needs some attention.

Your part looks good. No problem doing a little hand work when necessary. Sometimes it's easier than trying to get the machine to do it.

When you have a chance, try a good grinder and some HSS bits. You may find that custom ground bits are life savers - especially for tight spots.

I use inserts most of the time, but they tend to like a lot pressure and they "push off" a lot more than a really sharp HSS bit. That makes it hard to reduce a part by .001.

I can make a lot finer cut with HSS. The downside is they take some time to learn how to grind and keep sharp. It's probably worth the effort for us guys that don't have the most rigid equipment and have to make do with simple tooling.

Oh yea, one trick for getting a nice cut-off is to feather the angle on the tool to cut slightly more on the side ya want to keep. That will allow the good part to drop off clean and leave the niple on the bad side.


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## wquiles (Apr 26, 2006)

Thanks Mac and olephart - excellent tips and suggestions 

Much appretiated :rock: 

Will


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## cy (Dec 31, 2006)

nice proto..


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## wquiles (Jan 3, 2007)

Thanks 


Will


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