Author Topic: Depth Stop for Collet  (Read 1057 times)

Offline Steve Crow

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Depth Stop for Collet
« on: August 23, 2021, 02:13:17 PM »
I thought that this little device might be of use to someone.

I have made a start on the valves, guides and tappets for my model V8 and there are 32 of each of them, plus spares. To ensure repeatability, I decided to make a depth-stop system for 8mm watchmakers collets.

I started by making M4 tapped inserts for the back of the collets, in this case 2.6 and 3.0mm.



I then cut of the head of a long M4 screw and drilled 2.5mm holes at each end. In one end I "loctited" a M3 allen head screw turned down. The other hole accepts the actual depth stop.



I then made a couple of lock nuts from a scrap spur gear (hence the splines) turned down so they fit inside the drawbar. I then made a long and short depth stop for different purposes.



Here is the complete unit.



Some of the parts I have to make are very shallow so the long stop should be a great help.



The collets can be used normally when I don't require the stop as the clearance in the M4 insert is greater than the collet size so long stock will pass through.

Steve

Online Vixen

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Re: Depth Stop for Collet
« Reply #1 on: August 23, 2021, 02:21:54 PM »
Hello Steve,

That collet depth stop is real neat. I like it. Could the idea be applied to ER collets, which are widely used?

Mike
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Offline Dan Rowe

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Re: Depth Stop for Collet
« Reply #2 on: August 23, 2021, 02:50:25 PM »
Steve, nice I will keep that in mind if I need a depth stop on a watchmakers collet.

Mike, it seems to me that the internal screw threads have to be applied to the collet holder with the ER series so it would depend on the holder design. They make ER collet holders for both 8mm and 10mm collet both WW and D watch lathes so this would work on one of those.

Cheers Dan
« Last Edit: August 23, 2021, 06:40:54 PM by Dan Rowe »
ShaylocoDan

Offline steamer

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Re: Depth Stop for Collet
« Reply #3 on: August 23, 2021, 06:54:49 PM »
Dan's right on the ER.  That would be a challenge with ER.
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Online Vixen

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Re: Depth Stop for Collet
« Reply #4 on: August 25, 2021, 12:33:14 PM »

[/quote]

That collet depth stop is real neat. I like it. Could the idea be applied to ER collets, which are widely used?
Mike

Dan's right on the ER.  That would be a challenge with ER.

Well, I liked Steve's collet depth stop idea. I like the ER collet system. I also like a challenge.

I use ER collets on the lathe, also on the gear cutting rig and as tool holders on the mill. I figured a depth stop would only be relevant to the lathe.

This is what I came up with for my EMCO Compact 5 lathe. A length of 6.0 mm threaded rod, reduced in diameter at the business end. The threaded taper, taps into the rear of the lathe's spindle bore. The depth is set and locked from the rear of the lathes spindle.

Simple, neat, but not gaudy.










This simple depth stop has the additional advantage of working with both ER collets and a three jaw.

Mike





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Oh! sod the journey, lets hit the bar and pool instead.

Offline steamer

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Re: Depth Stop for Collet
« Reply #5 on: August 25, 2021, 01:01:17 PM »
Nicely done Mike.   My comments were directed at mounting a collet stop on an er collet.  That would be a challenge   mountingastop in the spindle is an obvious workable solution.
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Online Vixen

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Re: Depth Stop for Collet
« Reply #6 on: August 25, 2021, 01:22:53 PM »
Nicely done Mike.   My comments were directed at mounting a collet stop on an er collet.  That would be a challenge   mountingastop in the spindle is an obvious workable solution.

Yes, I talked myself out of attempting that particular challenge.  :Lol:

Mike
« Last Edit: August 25, 2021, 01:27:49 PM by Vixen »
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Offline Dan Rowe

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Re: Depth Stop for Collet
« Reply #7 on: August 25, 2021, 01:46:14 PM »
Speaking of ER collets holders I have them for 5C, R8, WW, and D collet mounts has anyone spotted a 3C ER collet mount? That would be very handy for my Levin with a 3C headstock.

Mike yes that works fine on that lathe I have considered a similar system for my Sakai lathe.

Cheers Dan
ShaylocoDan

Offline kvom

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Re: Depth Stop for Collet
« Reply #8 on: August 25, 2021, 02:12:16 PM »
I have a more common collet stop for 5C collets that I've used in the past to make studs in quantity.

For lathe, I can use parallels with my 6-jaw chuck as long as the part diameter isn't too small, otherwise soft jaws.

Offline Lew Hartswick

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Re: Depth Stop for Collet
« Reply #9 on: August 27, 2021, 02:39:51 PM »
I made a stop for the 5C collets at school . It worked fine.
   ...lew...

Offline simplyloco

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Re: Depth Stop for Collet
« Reply #10 on: August 27, 2021, 06:41:11 PM »
Hi Mike. I have an identical arrangement on my V10P. Works a treat!
John

Offline petertha

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Re: Depth Stop for Collet
« Reply #11 on: August 27, 2021, 07:58:37 PM »
I bought a nicely made (CNC via Asia) adjustable stop for my 5C collet for less than I could but materials. After using it for a while I started measuring final lengths & seeing a bit of variation even though with my cross slide locked to the lathe bed. Couple thou here & there. They were being faced on both sides (ie. not parting tool related). The stop pin is semi-spherical so should have been making consistent tangent contact only. There were no burrs or anything like that. It finally donned on me than any any tightening variation and/or slight diameter difference of stock, means that collet taper is slightly different, means the entire collet + pin is going in or out of the chuck axially & that was the source of discrepancy. So IMO, if you need the parts closer to identical, then the stop rod locked in the spindle tube (independent of collet) is the way to go. If its more about lopping parts in a more expedient manner & a bit of length variation is OK, the stops work fine.

Offline steamer

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Re: Depth Stop for Collet
« Reply #12 on: August 28, 2021, 01:01:24 AM »
I need to make me.some of these for my 3 jaw!   

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Offline Overbuilt and Overkill

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Re: Depth Stop for Collet
« Reply #13 on: August 28, 2021, 10:50:07 PM »
Fwiw and I'm unsure just how helpful this might be. Oddly collets and specifically ER collets are a bit more complex than most at the hobby level generally comprehend. While this video is mostly about high volume industrial level part production, it does detail some hidden tooling costs as tool run out increases with cheaper and more poorly manufactured ER collets. 
Exactly how important those hidden cutting tool costs may become for most of us over a lifetime of use is obviously up to each one of us to make our own decisions about. But the video does provide some less well understood information that many might not yet know about. So it's important information that imo is at least well worth understanding. Higher run out numbers do in fact have a detrimental and measurable effect on cutting tool life. Cheaper collets may not have quite the cost savings we might think.

Rego Fix are the recognized inventors of the now common ER collet system and I'd highly recommend subscribing to there YouTube channel as there's a lot of details and various options to pick up from there videos. https://www.youtube.com/c/REGOFIXToolCorp/videos Given the exact same angles used on the original Schaublin collets, I very much suspect Rego Fix used that Schaublin design as there initial starting point, shortened them a bit and added the extraction groove. Comparing my plain 25 sized Schaublin collets to the same ER 25 sized one's I have it appears Rego Fix for some reason shortened the collet length by 1 mm and added that extraction groove to be used with today's now standard eccentric nut design.

While I don't know the same holds true for other collet types and using an internal collet stop, Rego Fix has document proof that using a hard stop with ER collets does have fairly large effects on the collets holding torque and an increase in measurable run out in there two part video series.
and
t=3s Again I'd suggest it's an effect worth understanding and if judged important enough at least checking your run out if the same happens with other collet types.