Official Luthiers Forum!

I can't afford to buy a decent 3 degree reamer at the moment. I do have a reamer with a 4 degree taper. Will I "get away" with using this?

Has anyone tried these cheap looking things:
http://www.ebay.co.uk/itm/TECHNOFRET-3- ... 876wt_1170

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We are all in the gutter but some of us are looking at guitars.

Thanks for the unsolicited advert, Joe.

Joe: Depends on who will own the guitar and how fussy you are about workmanship. For someone else, no deal. For you, try the ream in a block of hardwood and check with both 3 and 5 degree pins. You may find one or the other a close fit that you can refine by working the pins a bit. Hope you have success.
Tom

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A person who has never made a mistake has never made anything!!!

LOL.....
Sounds like a good case to send one for a review!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I am just going to try to stay out of this thread, Colin ...I could explain how these flat reamers are CNC machined, and how they are hardened, and how they actually do cut as accurate a tapered hole as the Stewmac reamers ...but in the end, people will believe what they want to believe, and nobody who has bought a reamer at twice the price is going to be able to accept that there is a half price version which does exactly the same job, to exactly the same degree of accuracy.

I would also like to say hi to my friend Harry, who posted earlier on this thread under the pseudonym of "Morris Tonerite", attempting to stir things up, before his post got promptly deleted. Hope the convalescence is going well Harry ...Obamacare will see you OK, worry not .

the cutting action on those appears to be one of scrape/extrude with no real provision for centering in the hole other then eyeball, try-square and the 4 edges of the tool itself. kinda like the "reamer" you get mounted to a tubing cutter and certainly not a chip making tool of lasting quality.(sorry murray, but i'm 30 years deep in industrial tool design and i gotta call it like i see it )

on the other hand they are cheap, you're in the uk, and you are apparently ok with swapping a 3 degree taper for 4.

back in the day when i was a tool/die/moldmaker we'd make quick-n-dirty sprue bushing cutters by getting some O1 rod, hardening it, then grinding a taper and a chip gullet or two along the cutting length resulting in a self centering, and totally cheap form cutter.

functionally they will work. go for it

arie , I take on board what you are saying ( and I had taken all this on board before I ever started manufacturing these reamers) but the plain fact is that reaming a tapered hole in wood to accept a bridegepin, is a whole different ballgame from reaming, say, an internal Morse taper in a lathe headstock.

The 4 edges are self centering ( assuming that the operative isn't totally incompetent , in which case I would refund his/her money) and I wouldn't see any need for a try square ... the 3/16" hole is already drilled ...how far off could you go ??

Like I say ...we are working in hardwood ...and the object of the exercise is to create a tapered hole which will be a snug fit for an accurately tapered pin. Not rocket surgery ...not like reaming a Morse taper. Also , the countersink on the top of the bridgepin hole after reaming covers everything.

btw ... these reamers ream a totally accurate 3 degree and 5 degree tapered hole ...4 degrees don't come into it ...

-no worries
-give it to a child and see how far they will go off. kids are a great way to idiot proof a design. we used to do this in aerospace.
-granted the length of engagement is short.
-the op was interested in "getting away" with 4 deg vs. 3 deg -not implying you, (nor I for that matter). with modern cad/cam (not truly needed even), a decent mill, and a decent set up, it's pretty hard to f-up that geometry.
-the tool looks like it meets it's price point and intent. i only commented on a potential lack of centering. but since you have a generous warranty, i could use it once, claim i was totally incompetent, and get my money back. right?

i was an "ad man" for a year or so. i can set you up with some serious boosterism -for a fee of course.

Murray, I bought one of your reamers about a year ago and have been more than happy with it. Have you thought about making a slothead jig at half the price of the one I want from America?

Hi Derek, I have to say that I have not in fact contemplated manufacturing a slothead jig ...I am not sure that the market demand would be sufficient to justify the tooling up.

Murray, oops, I've PM'ed you.
For everyones elses information, at £17 each I think they are a very reasonable price. Reamers are one of the oldest metal tools. Undoubtably Murray's reamers work fine.
Actually, I'm more intersted in the first part of my question. But of course the answer is- try it on scrap. Just wondering if anyone has tried the same thing.

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We are all in the gutter but some of us are looking at guitars.

"give it to a child and see how far they will go off. kids are a great way to idiot proof a design. we used to do this in aerospace."

Give almost any tool to a child and see how far off they can go with it. I'm still in the sharpened tang of a file camp, which works fine for me.

Joe - to answer your initial question, yes, you should be able to get away with using a 4 degree reamer for 3 degree pins just fine. To be honest, I can't count the shops I've been in where a 5 degree reamer is all the techs ever used, even for 3 degree pins (often without even realizing the difference). Not saying that I approve of this practice, but on the other hand I've not heard much complaint (if any to be honest) of significant problems associated with this oversight either.

Bridge pin fit is not nearly so critical as say, violin tuning pins. The bottom is almost never tight, as the hole size required to fit all ball ends through is typically larger than the diameter of a standard sized pin where it meets the plate. Pins and the surrounding wood also tend to distort or compress over time. Martin for years fit their pins in a straight .200"-ish hole with no taper at all, which although this drastic disparity does indeed lead to problems, it still managed to pass the benchmark of "good enough" for a major manufacturer.

Fitting a 3 pin in a 4 hole however, should be plenty good enough in real terms. You're tighter toward the bottom edge where it really matters, and with only a few thousandths slop at the top end it won't take much wood compression at all to get a solid fit across a decent length of pin. If you want to do a dry run, drill a 3/16" hole in a piece of wood 1/2" thick, ream it to fit the pin, then after pushing the pin in a few times it should likely pass the 'wiggle test' just fine. You could even do a chalk fit test if you want to see how good the contact really is.

If reaming fresh holes on rare occasion is all you ever see yourself doing, then Murray's spade reamer should work just fine for a reasonable price. If you plan to do this work regularly or on any older instruments though, I would strongly recommend equipping yourself with good 3 and 5 degree semi-fluted reamers - they evolved in to their current design for very good reasons, and are certainly worth the price for a professional or semi-pro.

A conventional pin reamer is round for good reasons. If you're cutting with a reamer which only contacts opposite sides of the hole, what ensures you are remaining centered along the diameter at 90 degrees to the blade? What ensures your z-axis (depth and therefore diameter) remains perfectly constant when the blade is oriented along the x-axis relative to y-axis? Then of course there's the concern of chatter, which anyone who's worked much with reamers or chamfering bits can appreciate the value that a solid reference surface provides in a semi or single fluted cutter over a full fluted or spade.

Again, if you're only cutting fresh new holes on new builds, then a spade reamer may be fine for you at a lower cost. If you ever ream a pin hole that has string wear or has been slotted or ramped, or are concerned with the differing resistance to cutting on end grain vs side grain, or want to minimize any risk of chatter for an ideal fit, then you should save up for a proper semi or spiral fluted reamer. The standardized tool designs didn't come about just to make these tools more expensive, but rather to address and eliminate very real problems previously encountered by craftsmen in simpler designs.

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Eschew obfuscation, espouse elucidation.

Thanks, David. That's a very niecly written answer.
Murray has kindly offered to let me try his reamer and buy if I like it.
My 4 degree reamer is a conventional round one. I understand why this would be better.
So I'll try both and see what happens and report back.

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We are all in the gutter but some of us are looking at guitars.

I would be interested in one of these if you were to ever make one.

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Nick

Follow my musings on getting started in luthiery http://www.tredwellinstruments.co.uk