Reamer Resizing

[Wrist Pin]

Hi All
I need a .1230 reamer and I have two .1240 reamers in HSS. I plan to sacrifice one and make it .1230. I figure to chuck it up, turn at moderate speed and use a honing stone to get to the size I need.
Is this about right? Anyone care to comment?
Thanks
Jim

 

[Majorstrain]

I've heard that running a burnishing tool down the back of the cutting edge will shrink the cutting size a tad. BUT I haven't tried it, or needed to.
Just hear say on my part.
One of the more knowledgeable chaps will know for sure.

I personally would not hone it while spinning it in chuck. You would be removing the relief angle behind the cutting edge in the process.

Making a D bit might be another option. Plenty of info on here or MadModder about that, just do a quick search.

Cheers,
Phil

Not an expert by any means.

 

[MachineTom]

You can do that and it likely will work, the problem will be what size will it be when done, not an even .123" for sure, zero chance of a sharp edge, then it may lead to cutting a larger hole than .124. for the price on a reamer? does not make sense to me.

 

[purpleknif]

It'll work if you turn it in reverse.

 

[Mainer]

You can get a Lavallee&Ide 0.1230" HSS reamer from www.travers.com for 12 bucks.

I have serious doubts about your idea working very well. How are you going to keep the reamer a uniform diameter when you are hand honing it? The process will destroy the cutting edge along the flutes. That may be okay IF the largest o.d. of the reamer is at the front chamfer cutting edges so the sides don't need to cut. Otherwise, I think there is a good chance the reamer will bind in the hole.

On the other hand, it MIGHT work. If you have the time to spare and the inclination, give it a try and see what happens. You may get lucky. At least it will be an education.

Me, I'd pay the 12 bucks for an 0.1230" reamer....

 

[Springbok]

Hi
Have you thought about getting a expanding reamer honeing down a reamer is not for the faint hearted and can quickly lead to disaster for your workpiece. I have only seen it done once on a Quorne Cutter and that took the toolmaker almost 2 days it was for an extremly specialist job on a aero engine. I reccomend spending a bit of money on a new tool because you never know in the future you may regret attempting to modify that reamer as it was the size you now want.

Life is being in the workshop away from television and grandchildren playing computer games

Bob

 

[Ken I]

As per the other posts, I don't reccomend it - but as Purpleknife says it will work in reverse - that way the trailing edge gets more attention from the stone - forward you will end up with a hopelessly blunted and binding cutter.

You will also need to ensure paralellism - if any portion is tapered it will cut on very long edges and bind - unless this is only going through a short length.

2c

Ken

 

[dvbydt]

Make a "D" bit or buy a new, sized reamer, check that they cut the size you want. For any newbies, normal reamers only cut on the front chamfer, the flutes are cylindrically ground to size to act as a guide in the bore.

Ian

 

[steamer]

Actually for a standard size, IMHO....get a new reamer.

For odd ball or your in a bind. Make a toolmakers reamer

Turn up a piece of toolsteel to the exact diameter you want. File or mill flat the end on one side only to an angle of about 20-30 degrees. Now harden and stone the flat. For tools under a quarter inch, I wouldn't bother drawing the temper. just clean it up and use it.

I bet you can make a reamer faster than you can modify a multiflute one......JM 2cents......

Dave

 

[Wrist Pin]

Thanks guys, I appreciate all the input.
I am going to go for it. I have done this before just not a full .001 down in size. It is just a reamed hole for a press fit with 12L14 steel to steel and I may only have to go down .0005 in diameter to get what I'm looking for. Yes, I could buy one but I have no industrial supply store near enough. I would if I had more stuff to buy.

Purpleknife
Thanks for the reverse suggestion. That would be the way to go.

As dvbydt said, chucking reamers are ground cylindrically and only the front chamfer does the cutting. The flutes do have back clearance ground into them behind the radius but I don't think such a small amount of removal will matter. The reamer is only going in .125 deep. If I fail, I fail and I will buy one. As I said in the beginning, this reamer is an extra. I will let everyone know how I make out.
Thanks again.
Jim

 

[johnmcc69]

In my humble opinion..
ream it out. .125 with what you have. Since you're using a soft pin, "nick" or
prick punch the OD of the pin & press it in. This works well in most situations.

Hard pin/soft hole? Nick or score the hole.

Want your HSS reamer to cut slightly oversize for a slip fit? Take a cemented
Carbide lathe bit & slightly run it down one of the flutes of the reamer, slightly
As to "flare" the edge. Re-ream. Too big? See above....

John

 

[Ramon]

Hi Jim

I don't know if this is too late but just to confirm I too did what you are intending fairly recently on a 4mm chucking reamer reducing it a thou with a very smooth flat oilstone running in reverse.

It does work but, and it's a big but, its extremely easy to take it too far very quickly indeed and like others have cautioned once that happens you can't put it back on

You can bring it back a little by 'burnishing' the flutes by running something very hard and smooth up and down against the leading edge of the flutes but by the time you are doing this you are tending to be getting toward the 'losing control of the situation' stage.

However as they say "Ow'ts better than now't in't crisis"

Regards - Ramon

 

[Wrist Pin]

Thanks Guys
I will let you know how I make out.

 

[Wrist Pin]

Well, after a half an hour of spinning and checking, I had hardly made a dent in the diameter. My stone hadn't even taken a tenth off. I had done this before back in my tool crib days but I must have had a coarser stone to work with.
Anyway, attempt made, lesson learned, reamer ordered from Enco. Will be here Thursday. Thanks to all for your advice.

 

[Mike N]

How deep was the hole you needed to ream? Why not just bore it to size. They make small boring bars! Also once you made your .124 reamer dull from honing, it probably will cut undersize. I have a drawer full of reamers that are dull & cut under the size they actually measure.