Thread: Howto get sharp/square edges on an interiour feature

Once again i find myself scratching my head on this one,i have 2 plans so far both involving a fair amount of filing and fitting to the mating part, so i am sure theres a better idea out there, so how would you guys do this part? oh and for this one EDM is out as theres no local EDM equipped shop that has time to do it. Material is 316 Stainless.
Primary Dimensions in mm

Get it close with typical machining operations, then use a custom broach for the final profile. That would be a fairly simple custom grind.

Short of broaching or a slotter with quite a few tools and a lot of time, I'd put out a nationwide RFQ for EDM, courier / pallet services are cheap.

Wire

E
D
M

That is what you want. No local shop? Suggest you find one *someplace*
because this part begs for it. Otherwise re-design to eliminate the features
or make it in two parts, not one split but two.

Custom broach has *got* to be more expensive than finding a shop that can wire
it.

Jim

Shaper + rotary table would make quick work of this, with beautiful surface finish. Course, you probably don't have a shaper since you asked how to make sharp inside corners :p.

You'll probably have better luck finding an EDM shop than you will finding someone with a shaper.

Broach would be way big $$'s.

Finegrain

Second the vote on the shaper. I should have thought of that.

Jim

I have to admit i hadnt thought of a shaper, been having one of those days. However i do knwo someone locally with a slotter and hopfully he should be able to squeaze the job in on friday. If not ill get it close with conventional machining then file to fit the mating part. I have till tusday morning to get the part done, and some of the shops i have had a quote for edm for further up country cant garuntee it till at least wednesday which is fair enough.

why not make your own broach in the mill, turn a round piece and put the flats on it, drill and tap it to hold it in a mandrel, and heat treat it with a torch, thread it so you can bolt it to a round piece and put a pilot on it to keep it square in the slot.

Will it work if the inside look like this?
Maybe with a smaller radius on the arcs.

Another approach is to bore a 40 mm hole through the part, then machine a 40 mm round bar into two slabs to fit into the bore. Then silver braze the three pieces together before adding the through slot. There are simple tricks to keeping the parts fixtured correctly and getting the silver to flow without needing a loose fit between the parts. File small grooves lengthwise down the outer diameter of the filler slabs. The silver will flow down the grooves and bond the parts. Make an aluminum male part the size (high end of tolerance) of the mating part to keep the slabs in place while brazing. Silver braze will not stick to aluminum, or even British aluminium.

If brazing does not appeal, the two slabs could be fastened with flat head socket screws and not look bad at all.

Larry

Stewen unfortunatly not on this occasion i asked him about that its clamping the top of a rudder stock and he doesnt want any gaps that will accumulate dirt/water.

I had wondered about making up a broach to finish profile it, i think i may have some tool steel the right size too.

Larry the multiple part way would work, hadnt thought of that if all else fails ill do it that way thankyou!.

Originally Posted by sconisbee

Stewen unfortunatly not on this occasion i asked him about that its clamping the top of a rudder stock and he doesnt want any gaps that will accumulate dirt/water.

Why not seal it with silicone?

Originally Posted by Stewen

Why not seal it with silicone?

He's a picky customer:rolleyes:

Make it in two halves.

John S.

Originally Posted by sconisbee

He's a picky customer:rolleyes:

Oh,I see.

Hi I've got you a price for wire EDM

I will PM you

Kevin