Hand or Machine Reamers?

Whats the difference between hand & machine reamers?

Having searched online I see plenty of both, the difference I can see is hand reamers have the square on the end to fit a tap holder.

I'm looking to buy some, maybe Dormer to help with work on a Stuart James Coombes.

I'm thinking if I buy hand reamers I can also use these in the lathe Myford ML1

& pillar drill at slow speeds. Am I missing something?

Thanks...

.

Yes you are, Chris

**LINK**

https://en.m.wikipedia.org/wiki/Reamer#Hand_reamer

MichaelG.

Hand reamers have a long taper on the flutes, so full diameter is only reached once a third or more down the length. The taper is intended to allow easy starting by hand. Hence the square on the end for a tap wrench. Machine reamers cut on the very short chamfer at the end and as the name suggests are intended to be used in a machine, ideally a lathe or mill.

I never use hand reamers, only machine reamers in the lathe or mill. I wouldn't bother using them in a pillar drill. If a hole is important enough to be reamed it's most likely important enough to be properly located and drilled before reaming using a vertical mill. A hand reamer will not ream a blind hole. A general rule for machine reamers is half the speed and twice the feed of the preceding drill.

Andrew

Can you use a hand reamer in a machine? Yes, but the extra movement needed to get past the taper before cutting starts is a mild nuisance. Unlikely that the time wasted will matter in a home-workshop.

Can you use a machine reamer by hand? Yes, but you have to be extra careful to keep it straight. A hand reamer is easier to use.

Dave

Thanks Michael & Andrew Silly Old..., Ah great, that answers that then, more thinking to do, much appreciate your inputs on this!

Cheers

Chris.

Hand reamers are only useful for opening holes such as little end bushes in situ where it can't be done on a machine. Colin

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Thank you ALL so much for this info, the written answers and the links, most useful, helpful and enlightening!

Just be aware that any reamer can produce a very ugly hole. Perpendicularity to the hole is the key and as Andrew pointed out speed and feed are important when used in a machine. I have used hand reamers (by hand) in thick steel plate and had awful results. We often talk about reamers, but for a given diameter, there are many different sizes depending wether you need a loose running fit to a shrink fit. Look up limits and fits.

Also a little tip - If your reamer produces a hole which is a little tight, put a bit of rag around the reamer and pass it through the hole again. The rag will take up some of the clearance and make the flutes of the reamer cut oversize.

BobH

Using reamers is not quite as fool proof as you might think, even if you follow the rules. I always use machine reamers in a floating reamer holder. That way I get almost no cockups. Using a hand reamer quite often does not produce a round sized hole. This can happen with a sharp reamer that is used correctly.

I always play safe and use the floating reamer holder, it (almost) guarantees a good sized, round hole every time.

Andrew.

Thanks BobH & Andrew, off to look into floating reamer holders, something else Ive never heard of!!

Cheers

Chris.

Hemmingway do a floating reamer kit Chris - something I've thought about building but I finally decided that I'd better finish the other H/W kit I've got 'in-hand' first...

Regards,

IanT

Machine reamers can cut over size if everything isn't square.

Thanks IanT & Vintage engineer, yes just been reading up about them...and looking at the Hemingway option.

First of all it seemed to me counter intuitive to allow the reamer to follow the hole, but with an old lathe like mine (ML1) and of course my lack of skill & experience I can particularly see why it would be useful. So possibly not the best idea for me to make my own such tool with what Ive got, or lack of.

Useful info though and thanks again, I may see if I can find one with a 1MT to buy at some point.

Cheers

Chris.

Out of curiosity IanT what is the outstanding H/W kit you have yet to build?

Cheers

Chris.

Any reamer will cut oversize if it is held off centre. It will act like a boring bar and cut on one side only.

A floating reamer holder allows it follow the hole.

I made a floating reamer holder using ER25 collets for hand reamers with their parallel shank.

For Machine reamers with their Morse Taper shanks, I made up pseudo ER collets (only slit from one end ), with a Morse Taper bore to suit 1 MT, 2 MT and 3 MT machine reamers. They were ER 32 to accomodate the 3 MT .

Howard

To add to the reamer discussion, I always though a reamer was to 'take out the last few thou'.

However, having an interest in firearms, I was quite surprised to find that in the gunsmithing world a 'chamber reamer' actually cuts out quite a large amount of metal, starting with a parallel tube (the barrel) and forms the chamber for the cartridge to sit in. The reamer usually has a rotating pilot at the front and is best used with a floating holder in the tailstock to ensure alignment and concentricity.

And lots of suds down the barrel to clear the swarf.

That's exactly what I did with the last one I used, when my BSA A10 blew a piston to bits and I had to rebuild the top end where it was. 1974, I think...

Hand reamers have their place, like any other tool. The advantage of most hand reamers is that the taper is very useful in some situations where you may want a slightly tapered hole, or a tapered start to a hole. You may want to have a slightly oversized portion, and hand reamers will do this , as most hand reamers are in the 0.015mm to 0.02mm over the nominal reamer size at the very back of the reamer, depending on the tolerance range of the hand reamer being purchased.

I lap hand reamers down, to make special undersized reamers for press fit holes. The front tapered section is not touched. By undersized , it is only in the -0.02mm to -0.03mm to make a permanent press fit for pins.

Neil

Edited By Neil Lickfold on 04/10/2019 21:35:30

Hand reamers are like all cutting tools made to very close tolerances, of the order "+0.00* to +0.00* mm" to suit different hole standards. I have yet to buy a new reamer that is not on top limit. Usually H8 hand reamers are stocked, but special order can get you H7. With machine reamers usually stocked and produced to H7 tolerances, or again to any "hole fit" that is required, to special order.

A machine reamer usually cuts oversize when too much material is left in the bore, it will also wear quickly. Leaving too little material can also cause problems, usually giving a poor finish.

Another cause of hole size problems is by how slowly the reamer is passed through a bore. The process wants to be done quite swiftly, but at the same time the reamer must be allowed to cut. The correct lubrication is another area that will influence the size and the finish.

For a 3 mm reamer I usually use a 2.9 mm drill, for a 5 mm hole I use a 4.85 mm drill and for an 8 mm hole a 7.8 mm drill. In all cases I drill 0.5 mm smaller first before I use my pre-reaming drill. As can be seen the amount of material left in the hole for reaming is getting bigger with the increase in the size of the hole.

There is however a limit to how much that is left in prior to reaming and there are many PDF's by the people like Taylor+Jones who give guidance on this topic. The type of material being reamed is also of great importance. I would never expect a reamer that has been used on steel to produce a very good hole in brass or bronze. If a lot of reaming in the last two materials is envisaged it would pay to keep reamers specifically for these. I also never cut these materials dry with a reamer, despite what the text books might say.

I hope these notes help those who have struggled in the past.

Regards

Gray,