9/16" drill big enough for 5/8" reamer?

[coma13]

I'm going to be drilling a bunch of holes in 1/2" steel with a finished diameter of 5/8", which I will be reaming to.

The question is: is a 9/16" drill bit going to leave to much material? By my estimation, I should ideally be using a 39/64" but I don't have a bit that size and I'm not too eager to buy one.


Thanks

 

[sailah]

That's asking too much for a reamer in my experience. 1/32" is about the most I do on the lathe with lots of fluid. 39/64" drills are less than $10 on eBay.

 

[zkling]

I'm going to be drilling a bunch of holes in 1/2" steel with a finished diameter of 5/8", which I will be reaming to.

The question is: is a 9/16" drill bit going to leave to much material? By my estimation, I should ideally be using a 39/64" but I don't have a bit that size and I'm not too eager to buy one.


Thanks

What would you rather buy? A new reamer or the proper bit? Could sharpen the drill to cut oversize, but you could run into other problems (large out of round ness).

General rule of thumb is ~0.015" per side max when reaming.

 

[coma13]

New drill bit it is!

 

[Bondo]

Ayuh,.... When I drill 5/8" holes in truck frames, I use a 5/8" tapered ream, in a 5/16" pilot hole,....

 

[seans883]

39/64" is what i would use.

 

[abk241]

New drill bit it is!

A wise decision indeed.

 

[sberry]

Just curious. Whats the job that needs reamed holes?

 

[coma13]

Just curious. Whats the job that needs reamed holes?

Holes in a table top to use friction fit clamps with a 5/8" shaft.

 

[sberry]

I figured it had to be something like that. Try one by drilling it 5/8 and see if it works.

 

[larry_g]

I figured it had to be something like that. Try one by drilling it 5/8 and see if it works.

Agree and I would suggest getting a good stub (screw machine) length drill bit for the job. Not one of those floppy jobber length things.

lg

no neat sig line

 

[A_Pmech]

What kind of tolerance do you need on those holes?

 

[coma13]

What kind of tolerance do you need on those holes?

I'd like to keep +0.002 -0.000

 

[larry_g]

I'd like to keep +0.002 -0.000

Do you have a link to the clamps your using in these holes? They must be something special to have shaft tolerances that tight.

lg
no neat sig line

 

[coma13]

Do you have a link to the clamps your using in these holes? They must be something special to have shaft tolerances that tight.

lg
no neat sig line

Just copying the stronghand insertaclamp specs. I assume the tighter I keep the tolerance the more clamping force I'll be able to get out of them without slipping.

 

[ishiboo]

Just copying the stronghand insertaclamp specs. I assume the tighter I keep the tolerance the more clamping force I'll be able to get out of them without slipping.

I doubt that... as long as the clamp stays reasonable vertical I think you'll be happy. A drilled hole with a 5/8 bit should be fine.

 

[coma13]

Is that the consensus? 5/8" drilled hole will be close enough? That would definitely save me a bunch of time. I don't want to half *** it and end up regretting it further down the road, though.

 

[larry_g]

Is that the consensus? 5/8" drilled hole will be close enough? That would definitely save me a bunch of time. I don't want to half *** it and end up regretting it further down the road, though.

I'm with ish, a good 5/8" drilled hole should work. Before I went to the trouble to drill and ream I would have a couple of clamps in hand to mic before I assumed the hole tolerances you spec'ed above.

If I understand the workings of the stronghand system the most of the force is absorbed in the torque moment and little in the vertical linear direction. So close is good enough for fit because most of the force is in a perpendicular direction to the hole.

lg
no neat sig line

 

[A_Pmech]

Rotabroaches hold size better than a twist drill. If you're using a mag drill I'd use one. They run oversize a couple thou in general.

 

[rdn2blazer]

Usually the finish on the bore of a drilled hole is not great. Especially if there is runout on the spindle or the drill doesn't spin true. And there is usually always a bit of runout on a magdrill. There is decent good enough finish per application, but for a precision size with a "good" finish you want to ream it. Remember to stop the spindle before exiting the hole so you don't get swiling cutting on the exit stroke of the tool. Drills usually always do this especially after some use and tip wear and if any material builds on the cutting lip points. Drill it undersize, ream it, stop spindle, retract. Nicely bored hole everytime.

You could drill undersize then use an endmill after drilling to bore it too. Like a reamer but it will cut faster. Again if there is spindle runout it's going to cut oversized somewhat.

 

[coma13]

I'm using a mag drill with a drill chuck so I can't really swing the rotabroach.

I just got a 39/64" Silver & Deming style bit so I'm thinking if I can get away with a fairly small pilot hole, the 39/64" hole, and then a 5/8" ream I will be OK time wise.

Or should I just spot drill it and go straight in with the 39/64" Silver & Deming bit?

 

[zengarage]

I would spot it and then go after it with the 39/64th. It will save some time and will work out just fine. Lots of time is wasted stepping up sizes in my opinion. Just make sure you run that reamer on a slow speed and with a good amount of oil.

 

[mike13u]

If I'm not mistaken, those work like traditional 'holdfasts' or clamps that that go into dog holes in a wood workbench. As you tighten the clamp and apply pressure to the work, the clamp's shaft that is inserted in the hole 'pinches' the inside of the hole by being driven at an angle against the wall of the hole. The sliding section of the clamp (holding the work) 'pinches' the clamp's rail. These two pressure points hold the work firmly in place. Theory is no different than a standard Strong Hand (or any other) sliding arm clamp where two 'pinch points' (one on the arm and one on the work) create clamping pressure.
If this is the case, no need to do any more than drill to the size of the clamp's stud. The clamping pressure will hold everything together.

 

[Kevin54]

You could get by with a 19/32", ideally you want a 39/64", but trying to ream .063 is really pushing it for precision and it will prematurely wear out your reamer. If you have a good 5/8" drill, go slow, and use some oil, you may be better off.

I dug through my drill bits and I have one I can send you IF you send it back to me when you are finished. The shank is 39/64". I can turn it down smaller if you need. That is no big deal to me, what is a big deal is that I get my bit back. If it is dull, I can sharpen it when you are done, again, that is no big deal. Just PM me your address, and I will get it to you in the mail in the morning and you should have it Thursday.

 

[sberry]

100 s in labor and parts and maybe more in specialty clamps and the cost of a bit for something which in the end is near useless is a deal breaker?

 

[coma13]

If I'm not mistaken, those work like traditional 'holdfasts' or clamps that that go into dog holes in a wood workbench. As you tighten the clamp and apply pressure to the work, the clamp's shaft that is inserted in the hole 'pinches' the inside of the hole by being driven at an angle against the wall of the hole. The sliding section of the clamp (holding the work) 'pinches' the clamp's rail. These two pressure points hold the work firmly in place. Theory is no different than a standard Strong Hand (or any other) sliding arm clamp where two 'pinch points' (one on the arm and one on the work) create clamping pressure.
If this is the case, no need to do any more than drill to the size of the clamp's stud. The clamping pressure will hold everything together.

I ended up doing this. Drilling to 5/8" was satisfactory and my reamer was too long to be chucked up in the mag drill anyway.

You could get by with a 19/32", ideally you want a 39/64", but trying to ream .063 is really pushing it for precision and it will prematurely wear out your reamer. If you have a good 5/8" drill, go slow, and use some oil, you may be better off.

I dug through my drill bits and I have one I can send you IF you send it back to me when you are finished. The shank is 39/64". I can turn it down smaller if you need. That is no big deal to me, what is a big deal is that I get my bit back. If it is dull, I can sharpen it when you are done, again, that is no big deal. Just PM me your address, and I will get it to you in the mail in the morning and you should have it Thursday.

I got a 39/64" bit but ended up drilling to 5/8" anyway with a sharp bit and low speed.

100 s in labor and parts and maybe more in specialty clamps and the cost of a bit for something which in the end is near useless is a deal breaker?

Must have missed the 5th post in the thread huh? Don't you have anything better to do than whine about how other people spend their time and money?