Turning dilema

[JDenyer232]

Ok heres the situation. We have an sl-10 lathe, and they want me to turn a part that is 0.060" in diameter and 0.800" in length. Obviously this part is to small to use a live center on, and it tapers badly, the material is 360 brass. I was able to write a program that faces it down 0.005" at a time by using a subprogram in incremental mode. This eliminated the taper, but left tool marks that are about 0.0005" deep. The owner states that the surface finish needs to be nice and clean with no tool marks. I was able to get the finish by hitting it with emery paper and the owner was quite pleased. I am the head machinist for a microwave filter company so at this point its just R&D. Quantities are 500 pcs or less, after that I would send it to a swiss screw machine house. Anyone have any ideas, currently the machining cycle time is 5 minutes which I find acceptable, I just want to eliminate having to hit it with emery cloth for an additional 5 minutes to get a clean surface. Any ideas on how to accomplish this? Thanks in advance to all that reply.

[tobyaxis]

Ok heres the situation. We have an sl-10 lathe, and they want me to turn a part that is 0.060" in diameter and 0.800" in length. Obviously this part is to small to use a live center on, and it tapers badly, the material is 360 brass. I was able to write a program that faces it down 0.005" at a time by using a subprogram in incremental mode. This eliminated the taper, but left tool marks that are about 0.0005" deep. The owner states that the surface finish needs to be nice and clean with no tool marks. I was able to get the finish by hitting it with emery paper and the owner was quite pleased. I am the head machinist for a microwave filter company so at this point its just R&D. Quantities are 500 pcs or less, after that I would send it to a swiss screw machine house. Anyone have any ideas, currently the machining cycle time is 5 minutes which I find acceptable, I just want to eliminate having to hit it with emery cloth for an additional 5 minutes to get a clean surface. Any ideas on how to accomplish this? Thanks in advance to all that reply.

Try this:

Make a Center Post to use the Tail Stock.

Make the diameter a little smaller but long enough to use the tail stock.
Light pressure on the tail stock
DOCs should be very light .02.
Use a VNMG430 (330) insert.
Feeds and Speeds Very low.

I have done plenty of little parts like this.
If parts like these come in your shop it would be wise for your employer to buy a Swiss.

[Haas_Apps]

My guess is that you already have the brass otherwise I would eliminate the turning all together and just order the 1/16 rod.

http://www.sequoia-brass-copper.com/BraD360_rd-2bl.htm

[tobyaxis]

My guess is that you already have the brass otherwise I would eliminate the turning all together and just order the 1/16 rod.

http://www.sequoia-brass-copper.com/BraD360_rd-2bl.htm

LOL, that is the easy way, but very smart.

[CNCRim]

well it's brass quite soft, and you can try finish within one shot .75dia to .06dia it should work.

[cnc-king]

Ok heres the situation. We have an sl-10 lathe, and they want me to turn a part that is 0.060" in diameter and 0.800" in length. Obviously this part is to small to use a live center on, and it tapers badly, the material is 360 brass. I was able to write a program that faces it down 0.005" at a time by using a subprogram in incremental mode. This eliminated the taper, but left tool marks that are about 0.0005" deep. The owner states that the surface finish needs to be nice and clean with no tool marks. I was able to get the finish by hitting it with emery paper and the owner was quite pleased. I am the head machinist for a microwave filter company so at this point its just R&D. Quantities are 500 pcs or less, after that I would send it to a swiss screw machine house. Anyone have any ideas, currently the machining cycle time is 5 minutes which I find acceptable, I just want to eliminate having to hit it with emery cloth for an additional 5 minutes to get a clean surface. Any ideas on how to accomplish this? Thanks in advance to all that reply.

i dont see the problem. this is a pc of cake do it all day long on aluminum +/-.0005 on the dia tool must and have to be on center

[JDenyer232]

My guess is that you already have the brass otherwise I would eliminate the turning all together and just order the 1/16 rod.

http://www.sequoia-brass-copper.com/BraD360_rd-2bl.htm

Thanks to all that have replied, I would use 1/16" rod but here's the problem, we only have a 3 jaw chuck and the owner doesn't want to invest in a collet chuck just for R&D purposes. If this does become a running job then he would invest in a collet chuck so that I can just use a cutoff tool to cut the rod to length. Personally I want a collet chuck anyway, they are so much more versatile on smaller parts.

[tobyaxis]

Thanks to all that have replied, I would use 1/16" rod but here's the problem, we only have a 3 jaw chuck and the owner doesn't want to invest in a collet chuck just for R&D purposes. If this does become a running job then he would invest in a collet chuck so that I can just use a cutoff tool to cut the rod to length. Personally I want a collet chuck anyway, they are so much more versatile on smaller parts.

Mill a deep step the back of your soft jaws then put them back in the Lathe to bore the 1/16 Diameter. You will not need to buy any 16C's or 5C's just yet. Improvise......

[JDenyer232]

Mill a deep step the back of your soft jaws then put them back in the Lathe to bore the 1/16 Diameter. You will not need to buy any 16C's or 5C's just yet. Improvise......

Tobyaxis,

Thank you so much for the idea, I hadn't even thought of that. I assume you mean I should mill the back side of the jaws towards the pointed end away from the serrations, then drill a hole a little undersized to clamp the stock?

[tobyaxis]

Tobyaxis,

Thank you so much for the idea, I hadn't even thought of that. I assume you mean I should mill the back side of the jaws towards the pointed end away from the serrations, then drill a hole a little undersized to clamp the stock?

No your going to mill the serrated side of the jaws. Leave enough material to hold your part in the Lathe. Use a small enough drill to leave material for a small boring bar. Your boring bare will most likely be .05 in diameter. The problem is that .05 boring bars are very short. This is why I suggested milling the back of the soft jaws.

BTW: This is for the next time you have to do these parts so you do not need to buy any collets. Your company should consider a collet chuck though.

[JDenyer232]

No your going to mill the serrated side of the jaws. Leave enough material to hold your part in the Lathe. Use a small enough drill to leave material for a small boring bar. Your boring bare will most likely be .05 in diameter. The problem is that .05 boring bars are very short. This is why I suggested milling the back of the soft jaws.

BTW: This is for the next time you have to do these parts so you do not need to buy any collets. Your company should consider a collet chuck though.

Awesome, thanks for the idea, I will be running a few of these next week and I already have a new set of jaws to try this out with. This site is great, everyone here is so willing to share ideas to help others. Thank you Also thanks to Haas Apps for the link to the brass stock, I couldn't get 360 brass at 1/16 size from my usual supplier.

[tobyaxis]

YW