Group Project: Rotary Broach-- Building complete, all shipped out!

Sooooo maaaanyyy setups…..EVERY DAMN TIME…. Shimming against that damn 1* of tilt. ARRRGGGHH! Took like an hour to do 2 plates, 3/4” flat.
3 setups EACH on the lathe, one EACH on the CNC MILL, 1 setup EACH on the manual mill. Was there an easier way? I dunno.
D427A2BF-3660-47D1-8EF0-C628C53EC2BC.jpeg
 
  • Like
Reactions: rwm
GunsOfNavarone said:
Sooooo maaaanyyy setups…..EVERY DAMN TIME…. Shimming against that damn 1* of tilt. ARRRGGGHH! Took like an hour to do 2 plates, 3/4” flat.
3 setups EACH on the lathe, one EACH on the CNC MILL, 1 setup EACH on the manual mill. Was there an easier way? I dunno.
View attachment 371274
Click to expand...
When designing it, I figured the 1st op was to turn the back , then drill/tap the center.

Then, op2 is on the mill to cut the flats.

Op3 is to flip it over and put it on a sine bar in the mill vise, mill the front face, then drill the 4 holes with the DRO. The only "trick" there is figuring out how to find the "center", but I'm reasonably convinced an edge finder would have done the job.
 
ErichKeane said:
When designing it, I figured the 1st op was to turn the back , then drill/tap the center.

Then, op2 is on the mill to cut the flats.

Op3 is to flip it over and put it on a sine bar in the mill vise, mill the front face, then drill the 4 holes with the DRO. The only "trick" there is figuring out how to find the "center", but I'm reasonably convinced an edge finder would have done the job.
Click to expand...
I thought about so many things…. Again, in my head, this whole agenda was to make us get off our butts and do things we may not do. It’s obvious not everyone is on board for that same agenda…but I’m sending my parts to you with good warning…I’m not a professional and this was a bit of a stretch for me. I had to work constantly compensating for “error”, which was new. I have no sine bar so I had to figure out how to do this without that. I pushed myself for tighter tolerances (understanding some were a must) it was fun, but hopefully we’ll all discuss the final product rather than just being done when we get our broach.
How do I get (Erich’s) address without posting it here for the world?
 
Hopefully it will be ok! I messaged you my address.
 
So I got a really slow step 1 done today: cutting the 6" HSS M2 blanks down to rough size.

Unfortunately the braized carbide inserts I have just wouldn't cut it! I tried a simple facing operation and it busted the carbide and chewed up the HSS.

I guess I'll have to spend more time researching how to make this cut. I would not bother and do everything in the grinder, except this was my plan for the "dished" center.
 

Attachments

  • PXL_20210707_220959973.jpg
    PXL_20210707_220959973.jpg
    2.2 MB · Views: 9
HSS M2 sounds like a tough choice. I made my broaches out of O1. Then again, I would not trust them to last long on harder alloys. And- resharpening broaches is problematic since it reduces the OD of the cutting edge no matter how you do it.
Guns-nice looking surface finish on those parts.
Robert
 
Last edited:
rwm said:
HSS M2 sounds like a tough choice. I made my broaches out of O1. Then again, I would not trust them to last long on harder alloys. And- resharpening broaches is problematic since it reduces the OD of the cutting edge no matter how you do it.
Guns-nice looking surface finish on those parts.
Robert
Click to expand...
Yeah, I was hoping to make the best possible cutters I could, since they are so expensive otherwise. I'm a bit curious how I'm going to make this happen now though...
 
Yeah, that's rough. What's the answer? Whatever Robert was talking about?? I have two 12mm x 100mm round bars of HSS...but I believe you were using .500" diameter? Poop on a doorstep......
 
GunsOfNavarone said:
Yeah, that's rough. What's the answer? Whatever Robert was talking about?? I have two 12mm x 100mm round bars of HSS...but I believe you were using .500" diameter? Poop on a doorstep......
Click to expand...
Yeah, they are .500". I HAVE the material (and cut to rough size!), but I just have to figure out how to cut them on the lathe.. I seem to see that I could get some types of inserts that will cut it with little problem, but I haven't been able to make heads/tails about them. I guess worst-case I can try to make the dish on the grinder in some way...
 
I saw you have the stock....but I was picking up that it y be of a kryptonite mixture...
This is for anyone that may come across this thread way in the future... This adjustment seems to simplify the whole centering issues... just food for thought.
like.jpglike2.jpg
 
You must log in or register to reply here.
Back
Top