Needed Collets

[ScottM]

Ron,

I think masonry bits might be a bit flexible...

I'm not sure what kind of accuracy you need but if you drill the hole then put it on an arbor it may help.

I'm not horribly experienced but I'd do it in this order.

center drill
drill to size
ream if you have one
part off

chuck a piece of bar and turn down to the size of your hole leaving a lip to but the part up to
then either
1. glue it to the mandrel and cut both tapers
2. press it into the mandrel with a live center and cut the taper closest to the chuck
rotate and repeat for the other taper

leave the mandrel in the chuck after it's turned to size - I'm assuming you are using a three jaw.

YMMV

and make sure you have fun doing it :-}

- Scott

 

[ozzie46]

Scott

I have a 4 jaw and a 3 jaw but was drilling the collets mounted in the collet chuck to for the best accuracy. It didn't help. I contacted "Bogstandard" and he suggested boring the holes. I think that is the way I will go. I wanted collets as low as 1/16 th but I now believe that is not doable with my tooling and experience level.

The collets only have a taper on the rear.

Your mandrel idea sounds good. Do you think I could go as low as 3/32 and 1/8?

Ron

 

[ScottM]

Ron,

1/8, yea that may be a bit small for a mandrel.
It would probably work if supported by a center.

The idea I was tying to convey was that if you drill the hole,
Then use the hole as the reference for the rest of the turning
it should be concentric without boring the little tiny thing.
Same with not removing the mandrel once turned to size.

if Bogs says bore it - you should probably bore it.

little itsy bitty boring bar :-}


- Scott

 

[ozzie46]

Finished my collet tools. Yeah!! ;D ;D ;D

Collet material and blanks

tapering collet

Drilled then bored collets in the collet tool and chuck. Sorry no pics of that.
Forgot to take some.

Slitting Collets

Cheap slitting saw from h/ frieght

Burnt one up before I realized needed cutting fluid.

Secret cutting fluid. It worked great.

Finished product. I now have 8 collets ranging from 5/16 to 3/4 by 1/16ths.
I originally wanted them as low as 1/8th or 1/16th but found that I could not do them accuratley that small.

Thanks for all your help and encouragement.

Ron

 

[Tin Falcon]

Good going OZZIE
As far as small boring bars grind one up from an 1/8 cutter blank.
Tin

 

[ozzie46]

I had thought of that but didn't think it would be strong enough to bore approx 3/4 to 1 inch deep. You think it would work huh?

Ron

 

[Tin Falcon]

Ron :
Do you need to bore that deep ? I think if you are grabbing 4 times the diameter with the collet that should be enough. Relive the extra material from the back then drill and finish the hole in the front.
I just checked one of my ER collets the part that holds the 1/8 stock is only a 1/4 long . . The hole in the back is 1/4 inch diameter.
And checking a 3c 1/16 collet looks like grip length is about 1/8. So looks like 2 times the diameter is more in the ball park. So no worries mate
Tin

 

[ozzie46]

Tin

Thanks for the info. I have never seen a factory made collet so didn't know how they looked. That would save a ton of perspiration and tears.

Ron

 

[abby]

Good work on an interesting project , I make more tools than models. I collect old taper shank drills, the shanks are not hardened so you can machine them easily, it's a cheap source of accurate morse tapers as they are usually thrown away once the drill is no more use.