[PROJECT] Spin Indexer Tailstock

[EdK]

Time to get back to this project which got interrupted last November for various reasons. I'll post pictures as I go but here's a picture of what it will look like when I'm done.

Ed

   

[RobWilson]

Interesting design Ed

Who's design is it ?

Rob

[EdK]

Rob,

It was designed by a guy named Dick Kostelnicek and published in the March 2012 Home Metal Shop Club newsletter.

http://www.homemetalshopclub.org/news/12...pdf#page=5

I had the aluminum (aluminium) tube with 3/8" thick wall already, got it for free, so the design fits my available materials nicely.

Ed

[EdK]

All set up for tomorrow evening to mill the piece that keys the tailstock to the slot in the mill table. (Take note of the tool being used Pixman (Ken))

Ed

   

[DaveH]

(08-03-2014, 04:27 PM)EdK Wrote: (Take note of the tool being used Pixman (Ken))
Ed

You're using our Ken as a milling tool .......... poor Ken

DaveH

[PixMan]

(08-03-2014, 04:27 PM)EdK Wrote: All set up for tomorrow evening to mill the piece that keys the tailstock to the slot in the mill table. (Take note of the tool being used Pixman (Ken))

Ed

Noted. What material are you milling with it and what grade of insert do you have in it? Tell me and I'll give you come conservative numbers for cutting speed and feed rate.

Looks like 1018 steel and WKP35 inserts. While the book recommends 820 surface feet per minute, preserve tool life at 500 sfm. That's about 1000 rpm. Feed rate would be .008" per tooth, so .032" per rev or 32 inches per minute. That's cooking! If anything, slow the cutting speed but try to keep the inserts working on feed rate per tooth. Speed kills, not feed (unless excessive.) Don't dip below 350sfm, you'll be hammering the inserts. At a .075" depth of cut you would be pulling about 1.5HP at the spindle, so it'll be working.

[Mayhem]

Nice looking shoulder mill there Ed. Is this your maiden voyage with it?

Ken - if Ed was limited to a feed rate of 7.500 inches per minute and a top spindle speed of 2500 rpm (coincidently similar to a Kondia FV-1), what adjustments would you suggest? I'd imagine dropping the chip load would do it but by how much.

The online calcs I've tried won't allow the spindle speed to be altered without changing the SFM. At 2500 rpm and a .001 chip load it calculates the SFM to be 1309. I'd assume that dropping the chip load by that much wouldn't be ideal.

[PixMan]

Surface feet per minute (or meters per minute) are always a function of the diameter of a cutter and the RPM. Change one, the other has to change with it.

You want to avoid really light feed rates with coated carbide because you'd be just "rubbing" and wear it out prematurely. Always give it some work to do. In the case of a machine with a feed unit limited to 7.5" per minute, you could figure this out backwards easily. Divide 7.5" by (.005 feed per tooth x 4 teeth) = 375 rpm. A 2" cutter at 375 rpm is only running 196 sfm. That's really on the low side for carbide inserts, but they should survive.

[Mayhem]

thanks - I was trying to figure out how to keep the SFM up. Now I know why I couldn't do that.

[John S.]

You could also use a diesel truck piston and either face a bit off or add packing so the gudeon pin hole [ wrist pin for the cousins ] is on centre hight.