Cutting holes in a cavity

[solidNeutron]

Image shows a simplified version of my part. It is a stainless steel block made of 10 mm plate filled with lead. There is a cavity in the block 150x250x150 deep with 6xM10 holes in the bottom side. These holes have to be cut quite accurately because they are used to mount some precision equipment. I was wondering what the best manufacturing process for cutting these holes is. Thanks in advance.

 

[desertfox]

Hi solidNeutron

How accurate is quite accurate wouldn't drilling and tapping
suffice?


regards

desertfox

 

[solidNeutron]

Hi desertfox.

The holes should be within 50 microns. I also might have some holes for dowel pins. The cavity is relatively small, 150x250x150 mm deep.

Regards,

solidNeutron

 

[desertfox]

Hi solid

I would have the holes prior to tapping put in by a jig boring machine.

regards

desertfox

 

[solidNeutron]

Thanks desertfox.

I appreciate it.

solidNeutron

 

[GageDr]

If you are going to put in a couple of dowels, I would not use the the threaded fasteners for locating.

If you have a problem finding someone to jig bore 50 microns or less, I would find someone to jig grind the holes.

A good jig grind hand can hold both size and location too 2.5 microns or less.

Either way I wouldn't locate on the fasteners.

 

[KENAT]

Agree with GageDr that locating on the pin(s) is probably a better idea than using the threads, if at all possible.

Also even with this, if you use say 2 pins then making one of the holes slotted may have advantages. Effectively the pin in the very close hole gives X & Y location. The other pin just gives orientation.

Have you taken into account the position tolerances of the hole patterns not just on this but also on the mating part? ASME Y14.5 annex B has standard formula to help calculate this.

KENAT, probably the least qualified checker you'll ever meet...

 

[ajack1]

However you put the hole in can you tap a hole within 50 microns?

How much will you have to pay for a screw with the treaded part having an outside dimension tied up to 50 microns?

 

[GageDr]

The key is to locate positionally on a couple of dowel pins, and leave clearance around the the screw holes. This allows the fasteners to be used as just that, fasteners not locators.

 

[solidNeutron]

Thanks guys.

I'll use a couple of dowel pins and tap the other holes as GageDr suggested.

Cheers,

solidNeutron