[Jaynboom]

Has anyone made "bullets with set screws" to go in their 1/2" holders?

Or are you using an ER collet setup?

I don't really want to buy four ER collet holders and collets.

[GLCarlson]

I have the same problem. I'm frugal. That said, a set if ER collets is worth it, IMO.

[skray775]

I made one when Tormach had a lot of tooling on back order and the collet holder was not available. The bullet worked fine.

Has anyone made "bullets with set screws" to go in their 1/2" holders?

Or are you using an ER collet setup?

I don't really want to buy four ER collet holders and collets.

[WOTDesigns]

its definitely worth having a few ER holders. I have 3 and have had a few annoying set ups that needed 4 x 1/8 shank tools. wished I had another.

now I try to purchase as much tooling as possible with a step down for small tools (most are available in 3/8 or 1/4 shank), but some times it has to be 1/8 and I'm grateful for the ones I have. like my ultra duty .125" x 1" EM that gets a lot of work. it lives in its own er20 holder.

I wish I had the accuracy to make bullet holders... but I don't kid myself. increased run out would end up equaling the cost of the er holders in broken bits if I tried making them. I also would think they would need to have the weight of the screw balanced out like the newer tts holders to decrease vibration/run out at the tip.

[TXFred]

I'm making lots of set screw holders for large tools, on the theory that large tools don't care as much about runout.

This leaves my ER holders free to hold my 1/8" tools.

Frederic

[Jaynboom]

Are you folks using the Tormach ER collets and holders, or are you using another brand of straight-shank ER collets in a Tormach 1/2" endmill holder?

[Bob La Londe]

I have several brass bushings I made myself slowly reamed by hand on the lathe with set screws for my 1/4" collets, but for my 1/2" router I bought an ER 16 collet holder with a 1/2 straight shank. I cut it down to the depth of the router collet. I already had lots of ER 16 collets for my Taig.

I do have a set of Precise Bit collets for my Bosch Colt setup, but I find I reach for the bushings as often as not.

For a onesy twoesy job I think making a brass bushing is as good a way to go as any in a router. For something with a little more precision I would definitely go with a collet chuck though.

[Don Clement]

I use Tormach's ER collets to hold 1/8" bits.

Don

[RTP_Burnsville]

Tormach's ER series collet chucks.....

Robert

[Don Clement]

My bad. That be Tormach's TTS ER series of collets and toolholders http://www.tormach.com/product_tts_collets.html I am using specifically the ER 20 system but for 1/8" tools the ER16 system would work just as well.

Don

[Jaynboom]

Thanks for all the replies so far. I am using TTS.

Roy

[shred]

Are you folks using the Tormach ER collets and holders, or are you using another brand of straight-shank ER collets in a Tormach 1/2" endmill holder?

I can't think why you'd want to put a collet chuck in an endmill holder. I don't think straight-shank collets themselves exist. At least not ones that would work in a 1/2" TTS holder without a bunch of work.

I used to use the Maritool ER-20 holders with the thick body and 3/4" shank; they worked fine even without the TTS collar, but new Tormach holders are much cheaper than they used to be and also ATC-compatible, which the Maritools ones aren't, so the extra few $ is worth it.

[Jaynboom]

Oops. I meant a straight-shank holder like the Mari-tool. I didn't word that very well.

I forgot about the TTS tool changer compatibility. Thanks for the reminder.

[AiR_GuNNeR]

I've been making my own TTS holders and have managed to get the bore very accurate. What I have been doing is drilling the hold 1/64" undersize. Then I put the collet in the mill, and have a small carbide boring bar positioned straight up in the vise. The first skim I take just enough to clean up the hole, then take an additional .005" off. I put the holder back in the lathe and run a reamer through the hole. The end mills fit nice enough to pull a vacuum when you draw them out if you plug the spindle end with your finger.

I've made several 3/8" and 1/4" holders. I have a 3/16" holder on the lathe right now, getting ready to drill. I have not decided if I am going to use a single set screw and grind a flat on my mills, or go with a double set screw. I'll be using it with a 3/32" ball end mill, so it will see very little torque. I'll probably make an 1/8" holder as well, but I need to see if I have a carbide boring bar small enough.

[TXFred]

I've been making my own TTS holders and have managed to get the bore very accurate.

Nice looking holders. I have two questions.

What boring bar are you using? Do you have a part number?

How did you calculate the size of the balance hole?

Frederic

[Bob La Londe]

I would do it this way. Calculate the volume of material removed for the set screw hole. Multiple by weight per volume. Weigh the set screw on a grain scale (gunpowder scale should work). Subtract from previous number. Divide by weight per volume. Remove that volume of material from opposite side.

Yes, I know. Spin balancing might be better, but that should get you really really close.

[AiR_GuNNeR]

Nice looking holders. I have two questions.
What boring bar are you using? Do you have a part number?
How did you calculate the size of the balance hole?
Frederic

I don't have a number for the boring bar. I bought five of them off of someone in a forum. I'll post a picture of it later.

For the balance hole, it was easy to do with SpaceClaim. SC has an option to display and remove any solids interference. I created a 3/4" diameter sphere to emulate the ball nose eM I used to create the hole chamfer and balance dibbit. I pushed it into the surface at the set screw position, then had SC remove the interference. I then pressed a hex shaped solid into the surface, the depth of the actual set screw hole, and again had SC remove the interference.
Now for the balance dibbit. SC has a measure utility that gives the center of mass. I kept pushing the sphere deeper into the holder, opposite the set screw, and removed the interference until the center of mass returned to the centerline. After I had it close enough, SC gave me the distance into the surface I pushed the sphere.

[AiR_GuNNeR]

Here's a picture of the boring bar I used for the 3/16 holder.
By the way, here is the order of operations for making them, (and you want to start with the smaller diameter holders first).

1. Turn the OD to 1.500"
2. Turn the collet end first to a finished .750", and chamfer to 30 degrees..
3. Finish cut the shoulder that mates with the spindle face.
4. Cut the shoulder recess.
5. Drill 1/64" oversize for the cutter diameter you are making 1.4" deep.
6. Flip the part around and drill the spindle end 1/64" undersize.
7. Mount the part in the mill, and perform one skim pass and one .005" cleanup pass.
8. Mount back in the lathe and ream.
9. Finish turn the spindle end to final diameter and chamfer end at 25 degree angle.


A couple of notes, the reason you start with the smaller sizes first, and turn the spindle end to the final diameter last is because it's really easy to mess up and bore the hole oversize, or perhaps the reamer goes oversize on you. This gives you the opportunity to make a 1/4" holder from the 3/16, (like you were intending all along anyway right?)