ER32 in the 4 jaw

[epanzella]

Just finished yesterday's project. I occasionally need to make shafts for RC plane motors that turn from 10K to 20K rpm. They have to be accurate to a few tenths and need to be swapped end for end for finish machining. I made a Viper knock-off chambering fixture a few years ago for machining rifle barrels that worked out really well for me so I decided to make a mini version for doing things that spin. I like the range of ER32 collets so I picked up a collet chuck with a straight shank so I could dial it in axially and radially. Haven't machined anything with it yet but I dialed in some long dowel pins to a few tenths along their length without much trouble. I used the same 1/2x20 threads as my chambering fixture so I wouldn't have to make another set of brass tipped bolts. I made it with 8 flats so I could have the bolts between the chuck jaws or lined up with them. It doesn't seem to make much difference which way I mount it. Of course I can use this without the collet chuck as well for other stuff like chambering pistol barrels.

 

[DavidR8]

Nice work!
I’d be terrified of those bolts spinning around though.


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[Ulma Doctor]

Nice work!
I’d be terrified of those bolts spinning around though.
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The bolts are something to be acutely aware of, but you don’t be overly fearful of the set up. Just keep arms, hands, and clothes away from the mayhem and you will be just fine.

 

[Ulma Doctor]

Nice work!!! @epanzella

 

[ErichKeane]

Nice! I've been considering making one of those Viper-clones for a barrel threading project I have to do. Yours seems shorter than I typically see these (typically seem to be ~7 inches long?), so I'm curious how effective you find this on longer barrels? Or are you only doing shorter ones?

I've got a 3ft long headstock, so a headstock-side spider doesn't work for me :/

 

[epanzella]

Nice! I've been considering making one of those Viper-clones for a barrel threading project I have to do. Yours seems shorter than I typically see these (typically seem to be ~7 inches long?), so I'm curious how effective you find this on longer barrels? Or are you only doing shorter ones?

I've got a 3ft long headstock, so a headstock-side spider doesn't work for me :/

The unit in this post is a mini-version of the viper knock-off I made a few years ago which is for full sized for rifle barrels. My headstock needs a 24+ barrel to use the outboard spider which works OK with blanks but not on barrels that have been finished to shorter lengths. The big one works great so I have high hopes for it's little brother. Below is a pic of the full size one I made about 2 years ago.

 

[ErichKeane]

Ooh, thats great! That is almost exactly what I was thinking of making (right down to brass epoxied onto the bolts, and the flats for the 4 jaw!). I'm stuck in a bit of an 'analysis paralysis' on mine. I was thinking 7 or 8" long, and I know the Viper is 4" diameter (with a 1.5" passthrough), which looks about what you went with?

 

[epanzella]

Ooh, thats great! That is almost exactly what I was thinking of making (right down to brass epoxied onto the bolts, and the flats for the 4 jaw!). I'm stuck in a bit of an 'analysis paralysis' on mine. I was thinking 7 or 8" long, and I know the Viper is 4" diameter (with a 1.5" passthrough), which looks about what you went with?

The brass tips have 5/16 studs leading to a 3/8 shoulder. They were pressed into the bolts and then machined true. I don't know if epoxy would hold.

 

[DavidR8]

The brass tips have 5/16 studs leading to a 3/8 shoulder. They were pressed into the bolts and then machined true. I don't know if epoxy would hold.

Thanks for that detail, I was wondering how they were made.

 

[Aukai]

The bolts are something to be acutely aware of, but you don’t be overly fearful of the set up. Just keep arms, hands, and clothes away from the mayhem and you will be just fine.

Mayhem, I've seen his work on TV, he'll spoil your whole day.....