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Doing my first solo build and got to the point where I made a jig to cut .125 slot for saddle in the bridge . Using a dremel with variable speed, a dremel brand adjustable base, and a SM 1/8 carbide down cut bit. Slowly cut slot in stages in a test bridge and the slot came out about 20 thou oversize. Way too wobbly. I realize that I dont have the best tooling but what I have is similar to the setup used in the class I took and that turned out just fine. Suggestions please.

Use a 1/16" bit and a shim to do two passes at each depth. Go whichever direction causes the bit to pull toward the inside of the slot. Dremel bearings are floppy.

Also, do the first pass fairly deep. Otherwise the bit does not pull to the side that first time, but then it does on subsequent passes so you end up with a little ledge.

Run the Dremel at the highest RPM (yes there is slop) use an up cut bit so you clear the slot (down spiral are good for inlay) -- if you are cutting a .127" slot then make your saddles to fit by sanding accordingly -- that's what I'd do. The Dremel is what it is.

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Ken Cierp

http://www.kennethmichaelguitars.com/

If you've checked the bit size with a mic or digital caliper, then you would have to look at lateral slack in your jig, flex in the 2 guides, excess clearance between them, flex in the plastic base, runout in the Dremel itself, etc.
If the Dremel itself is recent, shouldn't be too bad, but looking at your rig, well, there's a few places it could go wrong.
Difficult to say without checking it physically
Place the sliding base between the rails and try moving it laterally, you'll probably find movement

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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.

Yes there is a little bit of movement side to side but only a little. I appreciate all the comments. I will redo the base from scratch so it's absolutely square and get a smaller carbide bit. My saddle is approx. 120 thou thick. so I need to tighten up by about 20 thousandths. Like everything else in making a guitar, there's more to it than you expect. In this case , the fit has to be right on the money or it won't work. Thanks.
Ed

If you have 20 thou slop then try a 100 thou diameter cutter and it may work out about right.

Its much easier to sand down a large piece of bone to fit an oversize slot. You can cut bone with just about any saw and sand to a nice tight final fit...

Good luck--

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The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

I respectfully disagree with that idea -- using a finer bit to plow a deep wide channel in dense bridge material is asking for more trouble. A better tracking sled is certainly an aide to precision. As pointed out again, above the answer is to fit the/a saddle to the slot not the other way around. Making a saddle is a fairly simple process.

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Ken Cierp

http://www.kennethmichaelguitars.com/

.

What! Is that your solution to every problem in life Clinch? Just throw a big pile of money at it.? hahaha I like to take that approach whenever possible.

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Also I would secure and maybe beef up the "guide rails" (if they are not glued to the base) - one screw at each end of a small section of wood or coving will allow flex.
Every little helps.

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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.

apply med.super glue to both sides of the saddle
NOT at the same time.
Let dry or accelerate
Then fit it to the slot.
Careful sanding!

then figure out what is wrong with you set up.
Mike

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Mike Collins

M-u-c-h easier to fit the saddle to the slot, as opposed to the other way around. You still want a solid jig and routing tool to make the slot straight and even.

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George :-)

Dremels just aren't good tools for this. If it's all you have or wish to invest toward a job you won't do often, then you can get by, but this means working within the compromises and, and knowing that if you look close enough there will be imperfections.

If a job can be done perfectly for quick and cheap, or if it does not demand perfection, I'll be the first one on board. For this job, I've tried about every arrangement out there, and concluded it certainly falls in with the old adage - "Quick, cheap, or perfect - you can only pick two".

I obviously have priorities of being to efficiently and reliably get perfect results every time, and this means making some serious investment in good tooling (not cheap). If you will only be doing this once, I can see trying to make it work with the Dremel, but I would recommend refining your setup on a good number of test cuts on scrap wood, then cross your fingers when you go to slot the final bridge and hope for the best.

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Eschew obfuscation, espouse elucidation.

David, do you have a recommendation for something between a Dremel and handmade jig and the CSM? Would you recommend the same type of guide rail setup that is often used with the Dremel, just with a better router? I drooled all over my phone looking at the CSM. It looks awesome for high volume shops or repairs that demand the highest accuracy. I'm just trying to strike a balance between moderate accuracy and avoiding sleeping on the couch.

My setup now is a set of guide rails and a dremel in the SM precision base. I use a 3/32 end mill from BQ tools.


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The Collins saddle mill is in a class of one.

There is no way to make a precision router and collet yourself and it has many, many other uses in building. A Dewalt 611 with a good bit and collet could cut a pretty sweet slot with your same guide set up. There is no guide system that will fix a Dremel. You will never regret getting a real router. Promise.

The trick here is to not try to cut a slot with the same size bit as you want the slot to be. Aim for a slot that is slightly wider than your bit dia. Make you first cuts until you get to depth and then shave the sides with a final very, very light cut.
Many ways to achieve this with shims or template guides etc. So make your slot a tiny bit wider in both directions and make a bone saddle to fit the now perfectly parallel slot.
Even with a precision collet and beefy trim router you will get better results with this method. And you do need a decent trim router.
L.

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Cut to size.....Beat to fit.....Paint to match.

As David and Link said, there are a lot of ways to improve. One of the best ways is to dump the Dremel.

I used a Dremel for this job for years, obviously abandoning it after much frustration. I used StewMac and Bishop Cochran bases, I pulled apart several Dremels to shim and tighten up the bearings (not the surest fit in a molded plastic housing), but the housing, the shaft all the way through, the collet - it's just not cut out for heavy or precise cutting. So step one in my opinion is to get a decent laminate trimmer, or something more solid and precise than a Dremel.

Next challenge is the plunge. Precise plunging while cutting is a pretty tough thing to find, even with decent motors and bases. The best results I got aside from the Cochran bases or our own mill, was to set up tall square rails like in David Farmer's base, so that I could start the motor tilted back and then drop it in to cut. This actually worked quite well for me, but any attempt to plunge the motor in the loosened base just leaves a lot of wiggle room unless you have a very solid plunge base (not often found on trim motors).

Then of course if you can lightly trim one side at a time as Link described, this lessens the load on the bit and everywhere else, and can help clean up entire sides without multiple passes at different depths. The challenge here is then to have a setup to help ensure your sides are cut parallel, as with Farmer's setup.

There are lots of ways to do it, and what you use will depend on what variety of conditions it will be needed for. If you are only cutting fresh slots on a few bridges off the guitar, there are tons of setups that can be suitable. If your job (and career income) relies on being able to make precise corrections on valuable vintage instruments, with high efficiency while minimizing risk of error, then systems like ours, or Frank Ford's, can prove to be well worth the investment.

Needs and demands cover a broad spectrum though. The Dremel though, I think barely fits the bottom criteria at best. Just too much slip and flex at every point from the shaft, to the housing and bearings, to the collets and bases. I think the best place to start is with a decent trimmer, and that will eliminate half of the problems before you even have to worry about the jig.

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Eschew obfuscation, espouse elucidation.

I have a Bosch colt which could work, but I think the 611 is easier to adjust depth on the fly. For my Bosch I have a collet reducer to take it down to 1/8" so that I can use the same end mills I use in the Dremel for routing rosette channels. I could maybe use that reducer with a 611. One can never have too many routers I guess.

The CSM looks sweet. Maybe one day. I know, I'll celebrate build #10 with a purchase!

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"Doing my first solo build....... and the slot came out about 20 thou oversize."

That's not too bad at all! First test on a new jig - you will soon learn how to deal with the "slop".

"Run the Dremel at the highest RPM (yes there is slop) use an up cut bit so you clear the slot (down spiral are good for inlay) -- if you are cutting a .127" slot then make your saddles to fit by sanding accordingly -- that's what I'd do. The Dremel is what it is."

Good advice! No additional expense for tooling involved. Eventually you will want to get a decent trimmer if you stay in the game, but it's nice to use what you have for the first few.

I could use the ca trick , since I just bought some ca from StewMac, but I think I like Dave Collins recommendation the best. I definately want the most control so I will switch my setup to use my Ridgid compact router from HD. I have only used it for cutting binding channels until now. Its not a plunge, per se, but depth is adjustable as well as speed. It only comes with s 1/4 collet, so I'll stop by my old workplace, MSC, to get an endmill with the cutting diameter I need. Thanks again to all who've offered advice to get me out of this jam. Much appreciated. This guitar is a graduation present , so I dont want to mess up.
Ed

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Hey Ed. Just to give you a baseline for comparison a well made and fit saddle should completely use the entire saddle slot front to back, end to end with no visible gaps. Any tipping forward or aft is undesirable as well.

The fit would be such that it's snug in the slot to the point of being able to lift the guitar off the bench a 1/2" (or higher) by the saddle only but not tight in the slot, just snug.

If using a UST (pick-up with an under saddle element) the fit is slightly looser so that the saddle can be removed with fingers only but will not tip forward or aft at all either.

Very important is that the bottom of the saddle slot is perfectly flat as is the saddle. This is also more important with a UST in use but still important even with out.

With all of this said you can see how .020 or even .010" of slop in the saddle fit for those who chase tone may be robbing us of something important. For those of us who rarely if ever these days will bring up that four letter, subjective word.... tone.... catch us in a weak moment and we may confide that saddle fit plays into tone too.

One last thing. When we make saddles although it's no biggie to make one end .005 fatter than the other end to fit a poor quality slot who needs it? It's easier to have precise, uniform slots that can be reliably measured and fitted with our saddles.

In our commercial, Martin repair and authorized warranty center work being able to cut a precise saddle slot is absolutely key to doing quality work and providing real value to clients. Martin offers their very nice bone, compensated saddles to Martin dealers and repair centers. These saddles are CNC made and very uniform in size and specs. With the ability to cut a slot exactly as we need to we can reliably take advantage of Martin CNC saddles for a near perfect fit that only usually needs a few swipes of the saddles to get that perfect fit.

Bet you never suspected that there was so very much to think about in a stinkin saddle slot, eh?

yeah .. the words 'problem' and 'Dremel' in the same sentence ... must be slop ....say no more ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

When I started, I was using a dremel in the SM base along with the circle cutter and the Perspex saddle slot jig.

Just about ANY laminate trimmer will do better.

I have now modified these to use a Makita trimmer with a 1/4 to 1/8 adaptor sleeve. An extra trimmer base allows me to leave a base fixed to each. Much betterer