Saddle slot - how snug do you like it?

[vandenboom]

While I have read that you don't want a saddle to fit too tight and that you should be able to lift it out using fingers only, I figure there is a fine line between too tight and too loose. I am using 1/8" saddles for the first time on a dreadnought and routed the slot (with 10 degree tilt) with a 1/8" router bit. Without any sanding, the blank goes in (to be expected I guess), and while it is a reasonable fit, I feel it is just a touch too loose.

So my questions are...
- would you use a 1/8" bit to cut a slot for a 1/8" saddle, or would you do it some other way to get a good fit?
- can you buy saddles that are deliberately a smidgeon thicker than 1/8" in order to have a bit more control over the snug fit?
- if you feel the fit is a tiny bit loose, are there any tricks to make it snug

Thanks. Frank.

[Kim]

Hi Frank,

I like mine just a tad over finger tight in so much that they 'can' be pulled with the fingers but you will be at it for a while but covered with cloth and lightly gripped with pliers they will pull very easy.

For a 1/8th slot I use a 1/16th downward spiral bit and widen incrementally. If you try to cut a 1/8th slot with a 1/8 bit there is a good chance it will wander and you will then need to shoot for a 3/16 slot to fix it up.

I like to cut the slot first and then work the saddle down with fine paper for a nice 'tight' friction fit. By the time it is polished out with micromesh, the saddle should be about where I like them to be which is a 'loosish' friction fit.

Cheers

Kim

[vandenboom]

Thanks Kim. Makes sense. I will glue a piece in the current slot and start again.
I keep reading about people's preference for spiral bits, but don't know what they are. I will source & buy a 1/16" spiral bit tomorrow.
Frank

[vandenboom]

...looking for spiral bit suppliers and discover there are different types - up cut, down cut and compression!! What would you use for a saddle slot?
Frank

[Kim]

Frank,

If your slot is a tad wide you can make your own custom width saddle from beef bone from the local butcher, takes a bit of frigg'in about but it works very well. If you needed to go out to 3/16 to get the job done then that's OK too. It just means you have more surface to get the intonation spot on.

As for the bits, the tungsten carbide bits that Stewmac sells are brilliant but brittle and expensive so you need to keep this in mind when working the hardwoods we prefer for bridge making. These carbide bits will do many 'light' passes before their blunt, but try to hog out too much wood in one go with something sooo fine and they will wander or snap and leave you most shat off.

The tip is go easy, you have spent so much time and effort (and money) to come this far so you have all the time in the world, especially when a replacement bit is on the other side of it.

Cheers

Kim

[Kim]

...looking for spiral bit suppliers and discover there are different types - up cut, down cut and compression!! What would you use for a saddle slot?
Frank

Like I said in the first reply down cut is the go Frank. My advice, if you plan inlay and binding and a few more guitars in the future, get ur'self a 1/4, a 1/8th, 2 x 1/16th and 2 x 1/32. That way you will make shipping worth while and take some of the nerves out of the equation with the smaller bits.

Cheers

Kim

[J.F. Custom]

Hi Frank,

Kim has pretty much nailed it with regard to fit and other advice. If its too loose, you lose the transfer you're aiming for; too tight and you risk having it not seated properly in the slot or damage to it, the bridge or top trying to force it in place during installation or replacement. The play you have found could also be from slop in the shaft/bearings of the tool you are using to rout with; let alone inaccuracies in the bit or saddle width.

Spiral bits are the way to go for sure - they cut more smoothly and easier due to their 'shearing' action. For your clarification - Down cut will push the chips down into the cavity meaning it is a bit unclear what you have cut, however they will leave a superior crisp top edge to your channel. Great for inlay among other jobs. Up cut bits eject the chips up and out. The potential is there however for this up-cutting action to leave a burr/furry edge to the channel. Just to confuse you, the reverse applies in a table mounted router and also for through cuts which then depend on the side you want the crisp edge... Then again, there are always the compression up/down cut spiral bits for crisp edges on both sides of a through cut...

Cheers,

Jeremy.

[vandenboom]

Sorry Kim - should have looked more closely at your first reply about the downward bit.
I will definitely try the bone from the butcher to solve the immediate problem, and include the suggested collection of bits in the next stewmac order.
Frank

[John Maddison]

... you can make your own custom width saddle from beef bone from the local butcher ...

There's a pretty good discussion about bone types and a description of how to prepare bones (by Alan Carruth halfway down the page) at this page on the Delcamp Forum. I've also read that leaving the boiled bones out in the sun to thoroughly dry after removing the fat can also assist the bleaching process.

[Rick Turner]

I use three flute carbide downshear bits from McMaster Carr. They're actually available in 1/64" sizes, so you could go with 7/64" and take two passes. I run mine either on a CNC machine or do the slots on a vertical mill. Works great.

Since I mostly make acoustic-electrics, I like a slip fit so the saddle doesn't hang up in the slot making for bad string balance with the pickup. I've been doing the tilt-back saddle thing since about 1991 or so, and I wouldn't do it any other way now.

[Kim]

I use three flute carbide downshear bits from McMaster Carr. They're actually available in 1/64" sizes, so you could go with 7/64" and take two passes.

Any other resource you can suggest for these Rick, McCarr won't deal with anyone outside USA since 9/11, it seems everyone else in the world has been deemed a threat to national security, even their brothers in arms

Cheers

Kim

[Rick Turner]

If someone in Australia wants to put together a group order for bits from McMaster-Carr, I can bring them over on one of my trips to Tasmania.

[Dennis Leahy]

I use three flute carbide downshear bits from McMaster Carr. They're actually available in 1/64" sizes, so you could go with 7/64" and take two passes.

Any other resource you can suggest for these Rick, McCarr won't deal with anyone outside USA since 9/11, it seems everyone else in the world has been deemed a threat to national security, even their brothers in arms

Cheers

Kim

Kim, you know I'm always here for ya'!

Just ask...

Dennis

[kiwigeo]

Youre coming over to Australia Dennis????

[Dennis Leahy]

Youre coming over to Australia Dennis????

Yes, if there's room on the oil rig for me! Oh wait a bloody minute, didn't you just say it was 0°? I might wait until warmer weather.

My 10 year old daughter has decided her dream is to move to Australia. And tend to the wild koalas. And be a professional chef. But all of that is after she wins an Olympic gold medal in gymnastics. So, yeah, there is a strong possibility that I'll be coming to Australia - however, that might be a while, so in the meantime, when you need stuff from "the States" (not including enriched uranium), I'll be happy to help.

Dennis

[kiwigeo]

27 degC forecast here in Adelaide today....unseasonally warm.

[Paul B]

If someone in Australia wants to put together a group order for bits from McMaster-Carr, I can bring them over on one of my trips to Tasmania.

Now, that's a nice offer. Thanks Rick.

[Lillian]

If there is a pressing need. Do a group order and I'll put them in a box or padded envelope and send them over.

[Nick]

Went to order something for work from McMaster Carr a while ago and found out that the American courts had slapped an export ban on them, stopping them from selling direct to overseas customers, something about their products have been found to be sold directly by them to countries deemed to be embargoed by the USA because of possible links with terrorism. Silly thing was we ended up still buying the McMaster Carr products but from another company that was allowed to export all of their product line, guess they were just abit more conscientious about who they sold too

[kiwigeo]

Whooooo...look out for the terrorist with the down cut spiral bit!!!! More dangerous than a thermonuclear device.

[J.F. Custom]

Whooooo...look out for the terrorist with the down cut spiral bit!!!! More dangerous than a thermonuclear device.

Now now...

If thrown exceptionally hard from close proximity with just the right flick of the wrist, thereby achieving high velocity with impeccable accuracy, they could probably just about do some damage to ones eye... ...one at a time of course.

Fortunately I have my solid micro carbide triple flute downcut chip breaking anti-terrorist protective device close at hand - otherwise known as sunglasses. Do you ??

The bonus is, if you are killed by the lob, possibly due to coronary thrombosis merely through the fear of potentially losing a valuable luthiers eye, you also manage to look cool dead

Jeremy.

[Dennis Leahy]

I've been looking on the McMaster Carr site for a suit of armor that can stop a flung carbide bit, but so far cannot find one.

OK, so are we actually talking about "router bits" or "end mills"?

Wherever I look, the router bits always cost more. I posted a question about end mills on the OLF, and several luthiers said they are using them. So, when my current downcut router bits wear out, I'll try end mills next.

Places to check for end mills and router bits:
McMaster Carr end mills

American Carbide router bits and American Carbide end mills

Carbide.com spiral router bits

Cutting Edge Technologies end mills

Note the shank diameter of anything you want to order, as you'll need either standard 1/8" and 1/4" shanks for Dremels, Foredoms and laminate trimmers, or else you have to buy end mill holders if the end mill shanks are some different size.

Dennis

[Nick]

Dennis, not knocking your plans I'm just not too sure how well end mills will work in a router situation. End mills are typically ground and sharpened for metal cutting, the geometries are different (cutting angles e.t.c ever so slightly) for these over a router bit. Many years ago when I first started mucking about with routers I tried a two fluted end mill (I know them as a slot drill, an end mill has 3 or more flutes) and it overheated and built up gum/residue on the cutting edges.
Now having said that I'm going to contardict myself! I quite often use a milling machine to route out the wood, especially when cutting the slotted headstocks. So I can only assume from this that the slot drills need to be run slower than the usual wood router bits. Two flutes would be the way to go if plunge cutting because they are sharpened so that they cut at their center, 3 or 4 flutes won't cut in this area so end up burning the wood, they work when cutting on their sides.
So if you have a variable speed router I would run it at the lower end of it's speed range.

[Nick]

Whooooo...look out for the terrorist with the down cut spiral bit!!!! More dangerous than a thermonuclear device.

[vandenboom]

Frank,
If your slot is a tad wide you can make your own custom width saddle from beef bone from the local butcher, takes a bit of frigg'in about but it works very well.

Thanks Kim and John FM (especially for Carruth link)
As you said, a bit of stuffin around, but a nice tight fit now. I'll never take an off the shelf saddle for granted again.
Frank