Lapping/Grinding services

[BMccarthy81]

I'm currently looking for a recomandation for a lapping/grinding service in the new england area. I've tried many places and asked for a flat & parrellel dimesnions of +/- .001 on some .200 A2 hardened steel plate.
Many times have I received the plates and they were warped or bowed. does anyone know of a well repitable shop that has great history on grinding/lapping?

 

[BillPSU]

I'm curious, what the overall dimensions on the plate?

 

[BMccarthy81]

The dimensions of the plate are 8.5 in. by 6 in. the thickness is .1625 in.

 

[unclesyd]

Here are three companies that I’ve delt with and got very good results. Your thickness is causing the problem, though it can be overcome. Just for curiosity what is the starting thickness?

Check out the GrindAll division

http://www.bostoncenterless.com/home.htm

Further away but very good.

http://www.tciprecision.com/index2.shtml

Out in the woods but do a very good job. I don’t know about your size but do an excellent job on smaller parts. give them a call.

http://www.alspi.com/machining.htm

 

[BillPSU]

Either your part starts out distorted or is distorted in the heat treatment process. When the grinder puts the part on his magnetic table it pulls the part down flat. He grinds the part, releases the magnet and the part returns to is distorted original shape. To grind anything flat with this kind of distortion, shimming the part during the grinding operation would have to be done very carefully and still you would end up with some flatness problems.
I recommend you review your parts prior to heat treat and after heat treat before grind and have an understanding on what is happening to the material for flatness. Another question is does the part need to be flat or is the thickness of the part the real consideration? If this part is being used as a spacer flatness may not be required.