OT: Should I bid on this job?

[btu44]

Hello all,

 

First I'd like to thank you all for all the help you guys have provided me. I'm mostly a 'lurker' but learned much by just reading.

 

The job...it is a small rectangular piece (.156" x .050") with simple 2D features on all long sides. It is to be made with Teflon type materials. Almost all tolerances are plus or minus .001". All deburr chamfers no more than .002". No coolant...only air jet. Quantity is 500 per month @ $5.00 a piece.

 

Here is what I think the tricky part is. I want to do this part at my home on a Tormach CNC mill. If your unfamiliar with this mill it is basically a Bridgeport CNC conversion. R8 collet, 5000 RPM max., 64 IPM rapid, about .001" backlash in X & Y and .0015 in Z, manual tool change with preset heights.

 

I am a CNC mill machinist of just 3 years but have become unemployed since the beginning of the year. So I have more time than money and my overhead is very low.

 

At my old job, it was a aviation job shop with newer OKUMA mills. I had no problem holding plus or minus .001" on those OKUMA's but this Tormach maybe asking to much. Now I've heard the saying many times 'A good machinist can make up for a bad machine' but still?

 

Any advice will be appreciated.

 

Barry

[Bruce Caulley]

I have a Tormach in my garage and could hold that tolerance no problem.

 

Go for it.

 

Bruce

[Bruce Caulley]

I have a Tormach in my garage and could hold that tolerance no problem.

 

Go for it.

 

Bruce

[High Sierra Plastics]

Do you have a way to accuratly check the dimensions would be my first concern.

[#Rekd™]

Hi BTU,

 

I would do it. Just be careful with temperature changes on Teflon like hot water.

 

John

[btu44]

Thanks for the advise. I'm thinking on giving it a go.

I do have some investment to make. A measuring microscope and a real air compressor are first on the list.

 

I am trying to come up with a work holding method. Even a small vise would probebly distort the part to much. Any suggestions?

[Ray H.]

The tolerance is the least of your worries with that thin of teflon.What are the geometric callout if there are any (parallel especially). Also having cut alot of teflon I would be very leary about the deburring.

[CAM-mando]

quote:

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I am trying to come up with a work holding method. Even a small vise would probebly distort the part to much. Any suggestions?

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Can you come up with a layout that incorporates multiple parts into a larger sheet or strip and tab them?

[JNO]

quote:

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I am trying to come up with a work holding method

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maybe a custom vacuum plate to hold a few pieces at a time?

[Kevangel]

I have also seen optical comparators sell for almost nothing at auction, I added a 14 inch with lenses to 50X for around $200....1000 lb. also had 10X, 20X lenses, surface illumination does not work at the moment.

[Newbeeee™]

I would try and go for multiple in a sheet and hold with vacuum.

Tool changes will be amortised this way.

Vac pumps are cheap off ebay. We have a couple of airconditioning pumps we use at work. Cheap and reliable.