-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Question on Atlas lathe endmill holder...
- Thread starter 56type
- Start date
- Joined
- Dec 25, 2011
- Messages
- 10,525
Using a tapped hole through all of your "made by you" reducing bushings instead of a drill-through hole would work I suppose but (a) it would be a lot of extra work for zero gain and (b) assuming that the thread start would have to match the thread finish in the holder within one degree, the odds are 360:1 against you ever finding another cutter holder that those bushings would work with. So if you use a hole instead of a slot, use a drill-through hole, not a threaded one.
Thanks, I'll go with the drill-through hole instead of taking the extra trouble of trying to tap the set screw hole.
- Joined
- Apr 8, 2013
- Messages
- 1,982
Not sure if I understand exactly what you're doing but If you're making something why make a bushing to be used with a holder. Just make the holder to fit the end mill and put a set screw in it for the Weldon flat. I use a straight shank for the lathe and stick it in a 3 jaw. The reason you shouldn't stick an end mill into a 3 jaw is that they're both hardened. A mild steel adapter works just fine.
Attachments
Since the end mill holder I have was missing the bushings it originally came with I was looking to make replacements initially. I had avoided using the 4-jaw to hold the end mill for the reasons already mentioned. I was planning on using the original end mill holder since it located in the MT of the spindle and so would be centered each time it was used with no need to dial it in with the 4-jaw ( haven't gotten a 3-jaw yet).
Also, my thinking was that the setup once installed, would be easier to swap out different size end mills by just loosening the set screw and pulling the bushing in current use and swapping it for the next size needed.
- Joined
- Dec 25, 2011
- Messages
- 10,525
epanzella,
The milling cutter holders marketed by Atlas had a 1/2" inside diameter by 2MT (for the 6" lathes) or 3MT (for the 9"' 10" and 12" lathes) that was drilled and tapped for the 3/8-16 common draw bar. And for smaller diameter cutter shanks they supplied a set of four reducing bushings in 1/16" increments down to 1/4". They were NOT intended for use with Weldon style cutter shanks. As I discovered the hard way.
They also sold several types and sizes of end mills and milling cutters that were suitable for use in their holders.
As far as using milling cutter holders made for smaller diameter shanks, that would be OK except that all of them that I have personally ever seen had the tanged style of Morse Taper, not the draw bar style. Do NOT use these unless you first convert them to draw bar style as they are guaranteed to pull loose and ruin your work. And your day or night!
I have the original Atlas part with the 3/8-16" thread draw bar. Just need to make the suitable reducing bushings to use it with smaller shank endmills. I planned on making both imperial & metric sized bushings to use with the endmill holder. I had noticed in the Atlas ads for accessories that various cutters were offered, though I have no idea of the contruction of those particular cutters (i.e. were the shanks not quite as hard as the cutting surfaces ??). Seemed to me a round hardened shank endmill being held in place by only a set screw could spin as easily as if it were held in a 3 or 4 jaw chuck, henca why I was asking about the bushings with the weldon shanks. With the weldon shanks having a flat surface for the set screw to bear against I saw no way for the endmill to rotate in the holder.
That's what I hoped to accomplish with this thread, to get a best case design for making reducing bushings that both work with the endmills on the market today and that wouldn't sieze themselves to the bushing/holder. So far it looks as though I'll make the reducing bushings from O-1 or W-1 drill rod, with a clearance hole to allow the set screw to pass through and contact the flat weldon shanks on the endmills.
If anyone thinks this won't work or will cause the siezing problem of the endmill locking itself into the bushing and holder, or the choice of material is wrong, let me know and I'll make changes. Thanks.
That's what I hoped to accomplish with this thread, to get a best case design for making reducing bushings that both work with the endmills on the market today and that wouldn't sieze themselves to the bushing/holder. So far it looks as though I'll make the reducing bushings from O-1 or W-1 drill rod, with a clearance hole to allow the set screw to pass through and contact the flat weldon shanks on the endmills.
If anyone thinks this won't work or will cause the siezing problem of the endmill locking itself into the bushing and holder, or the choice of material is wrong, let me know and I'll make changes. Thanks.
- Joined
- Apr 8, 2013
- Messages
- 1,982
If you use a bushing inside an end mill cutter with no setscrew how do you hold it in? All the end mill holders I bought or made had a setscrew for the weldon shank. If the endmill didn't have a flat already I ground one in. The MT holders all had draw bar threads, the untapered holders were soft and did not. I used them in a lathe chuck. The holders for my mill have R8 taper and draw bar threads. So does my ER32 collet chuck. I also have a 1 inch straight shank ER32 chuck for my lathe but It's hard so I have to tape it for chucking.