[CoolhandLuke]

Here's the deal...I am turning parts on my cnc lathe and parting them off. The threads are thru and I want to deburr the cut off side. When I do it, it throws a burr into the threaded hole and a bolt won't start. I don't want to tap them. Is there a tool to use to deburr hole so i don't have to retap them?? I have 12k parts to run.

Thanks all

[flick]

Is there room in the hole, or is it of a reasonable depth that you can relieve the backside of the thread with a boring or grooving bar before threading?

[Delw]

I assume your cutting ID threads?

cut a relief in the back side before you part it off.

the best way is to
chamfer, bore and do relief
cut thread
chamfer Bore and relief (drypass)
Cut thread (dryPass)
part off.

end no burrs what type of material

[ImanCarrot]

Could you put a grub screw in before you part off (less than the thickness of the parted off part obviously), part off, de-burr then screw the grub screw in and out?

You could use one of them battery hand held drills with a hex head attachment to speed it up.

Or what about a cone shaped grinding thing- would that leave a bur?, you could make a fixture to locate them on the drill press and zip through them.

[mactec54]

CoolhandLuke

Do like the other posts have said or simuilar , with a boring bar that the insert is on a 30deg or what angle, you want to cut on the inside of your part, Do this in before you thread it, & then part it off

[CoolhandLuke]

The thread is 5/16-24 so it would tight to get a boring bar in and relieve it. The part is 2.125 long so I would have to hang it out a good ways with a really small diameter.

I have tried a burr set. Like the other guy mentioned...the one that you typically use in a diegrinder.

Tried a carbide countersink RH chatterfree 6 flute

HSS countersink single and multiple flutes.

The only thing I can think of is if they have a left handed deburring tool where it peels the chip out instead of down in the threads. Retapping sucks even though we have a tapomatic on a drill press. I don't want to have the extra 5 seconds in them LOL.

[CoolhandLuke]

These are aluminum

[wildwestpat]

Suggest you change the parting tool front clearance so that the parting off bur is on the chuck side not the part side. This should leave a square ended treaded hole and there may be a bit of a tear as the parting tool breks out on the last bit of the thread crest. This is easily removed with a snail type counter sink which could be a simple hand held routine - one quick twist - depending on how many you need to make!

Regards - Pat

[mactec54]

CoolhandLuke

That bore is quite small & long, another way is make the blank & tap after

[CoolhandLuke]

That still doesn't get me anywhere. I want to run the part on the machine and have it tap them. Get them out of the parts catch and burr and i'm done. I want to eliminate retapping them. I have to put a small chamfer on them so the screw starts and goes in and without a burr.

[flick]

This might be a situation where the costs of a single setup aren't worth the gains. Fewer setups aren't always faster. Estimate your net handling time to do these in two ops. It might be faster than dicking around with deburring after the fact.

[kling8]

depending on your call outs, I have used an oversize tap to get some forgiveness, How big of a chamfer do you need can you knife it out just enough to take the sharp edge, or do you need to meet a called out chamfer?

[RomanLini]

Use a cheapo 5 sided countersink tool chucked into a drill press. These deburr threaded holes quickly and easily and I've never needed to re-tap or mess with the thread afterward.

A cheap 5 sided tool might be best, mine are a bit blunt and don't "pull" the edge of the thread when countertsinking. A sharp countersink would be worse, especially if it has less than 5 flutes.

[metalworkz]

I find that the Weldon type flute-less countersinks cut very clean compared to fluted tools, and there is normally no chatter marks either.
They will usually cut the material in a single chip, and leave little or no burr.

Regards,

[CoolhandLuke]

Just to break the edge. I have a left hand drill I'm going to put a 90* point on so I can use it as a countersink. It should peel the burr up instead of right hand...rolling it into my first thread.