Binding cutter-comments please

[blackalex1952]

I have been using the LMI binding cutters in a router trimmer with a base I made that has an extra guide bearing, which effectively gives two guide bearings which ride along the guitar sides

binding_pic1.jpg (4.8 KiB) Viewed 15665 times

. One bearing is on the binding cutter, the other on the trimmer base.It is a clone of the one in the picture I have uploaded.I have found that it is easiest to use with the trimmer mounted upside down a la router table (in a vise) and the work moved against it, rather than trying to secure the guitar and move the trimmer and jig freehand. What I am wondering is: would the cutter and router bit shaft work in the configuration that I have sketched, ie, two cutters mounted on a common shaft? I have left out of the drawing a locking collet that would locate the top shaft mounted bearing, the one at the bottom would be held in the usual way with an allen screw.

[kiwigeo]

The kit in the photo is the Luthier Tools binding cutter which is a Williams style jig. I have one of these which I run with a Porter Cable laminate trimmer. Anything from Luthier Tools is going to be a very well and precision built piece of kit and this kit is no exception.

Note that on the kit in the photo the bearings don't run on the same shaft as the cutter as in your drawings. The laminate trimmer (and attached cutter) needs to be able to move in and out independently of the bearings to allow adjustment of cut width.

[blackalex1952]

I understand that, Martin. The jig I have made works on the same princible.But what I am thinking is, why not an extended shaft trimmer bit with double bearings,ie. you change both of the bearings. It would eliminate the need for a jig, and the cost would still be less than the cost of a jig! Even with an optional plastic router base designed to allow for the top curvature.The time saved in accurately adjusting the jig's bottom bearing to match the cutter bearing would also be eliminated. A lot of workshop tool storage space also saved. The one I made was a rough prototype, but it works so well, I moved on to getting my binding ledges cut! Locking the jig in a vise in a bench at waist height was also a major breakthrough for me.Not shown in the pic is the plastic base that allows for curvature of the top. By the way I christened the jig the "Enterprise"...

[jeffhigh]

A long thin shaft would be too flexible IMHO,

[kiwigeo]

I understand that, Martin. The jig I have made works on the same princible.But what I am thinking is, why not an extended shaft trimmer bit with double bearings,ie. you change both of the bearings. It would eliminate the need for a jig, and the cost would still be less than the cost of a jig! Even with an optional plastic router base designed to allow for the top curvature.The time saved in accurately adjusting the jig's bottom bearing to match the cutter bearing would also be eliminated.

Um I don't think you understand how the Luthier Tools jig works. You don't touch the two bearings.....they're fixed. To adjust the width of the cut the black guide shroud above the top bearing gets moved in and out by the silver adjusting screw at top right. Height of cut is adjusted by moving the trimmer up and down in it's holder using a knurled wheel (not visible in photo). The black screw on the side of the vertical section is the locking screw for the in/out adjustment. Unlike jigs that use sized bearings with the Luthier Tools jig you have an infinite variety of depth and width settings.

[blackalex1952]

On my jig, the bottom bearing is adjustable, the top one is the standard set of interchangeable bearings that came with the cutter. ie. change the top bearing then align the bottom bearing, which runs in a tongue and grooved guide channel.The locking screw goes into the threaded brass rod that can be seen on the side of the device.Depth of cut adjusted by the trimmer itself.I still think that my double bearing shaft would work, perhaps with a 1/2 inch shank rather than a 1/4 inch one, if flexing was an issue. I have been aligning the bottom bearing with whatever top bearing I choose using the back of a small engineer's square, accuracy is not that critical, and a test cut on a scrap of wood is always a good precaution.I do like the $300++ US model, but hey, we are musos and luthiers...maybe I will win a lottery one day and buy a whole factory of slaves for my hair brained ideas! The only drawback to my design that I can see is that the shaft length would be fixed, so thinline instruments would need a shortened shaft version,

[blackalex1952]

My other comment re the US made jig is that, given its cost, if I can make a guitar, I can make my own copy of the same jig out of wood or scrap aluminium and some tired old bearings from a re built power tool! I need to put my money into wood, finishes and guitar fittings.
Mario Maccaferri made all the jigs for the Selmer factory! In fact, if anybody is interested, I have made a "pliage" bending jig with its own heat pipe ( the angle is set by an adjusting screw and churns out consistent results), an angled Selmac soundboard shooting board, my own heat bending iron using chinese heating elements, a stewmac style binding thicknesser, a vacuum bagging system, go bar deck and all the usual other stuff. Happy to help people starting out, as I have been for a while. Love this forum also, the best one on the net! Great work everyone! A luthier who makes mainly folk instruments asked recently, "How are your Selmer Maccaferris going?" I replied: "I've got more jigs than an Irish songbook!"

[routout]

I just use one of these the Dremel fits straight in easy adjust fine increments see through and the Drem comes in handy for other things.

[kiwigeo]

I just use one of these the Dremel fits straight in easy adjust fine increments see through and the Drem comes in handy for other things.

I tried a Dremel for doing binding channels but the bearing play and lack of guts lead to me switching to a small router or laminate trimmer for this job. Sometimes you'll get a machine that works ok but generally the quality of Dremels has gone down hill over the years.

From the photo it looks like youre working on an instrument with a relatively flat top. Looking at the design of your jig (it's registering off the top off the instrument rather than the side) I'm wondering how it would go on an instrument with a domed top?

[blackalex1952]

Martin I am not sure who you are asking, me or rocket. The jig you have and the one I have works roughly the same way, with a guide running against the guitar top. It could be modified to accommodate quite high arching.My current OM build has a 25ft top raduis and my jig is fine for that.
Here is a link to Chicagoen luthier Dan Koentopp's page.http://www.koentoppguitars.com/
Dan makes archtops and believes that the top and back shouldn't be carved to match the sides on a cutaway, but should be the same arching as a non cutaway model, thus giving the plates more freedom of movement.I think he uses a pin router, big machine...Benedetto has the same kind of machine in his video.See pic...Opinions welcome!

[kiwigeo]

Martin I am not sure who you are asking, me or rocket. The jig you have and the one I have works roughly the same way, with a guide running against the guitar top. It could be modified to accommodate quite high arching.My current OM build has a 25ft top raduis and my jig is fine for that.

I was referring to Routout's Dremel jig. It's looks pretty much like a standard laminate trimmer jig and because it registers off the top with only one bearing running on the side it will tend to make a tilted cut once there's any doming on the top.

[blackalex1952]

Sorry, I meant routout. I agree and the dremels are a bit underpowered.

[routout]

Oops yes that was mainly for the flat top the rem are kind of OK if you take it easy a good starting point I guess.I have seen the side guide type without bearings just a strip of nylon attached as effective as any other on the market or the making of a clamping jig to level the body and a free standing router .

[blackalex1952]

I'm wondering about the binding on the Koentopp guitar... How to?

[Nick]

Dan makes archtops and believes that the top and back shouldn't be carved to match the sides on a cutaway, but should be the same arching as a non cutaway model, thus giving the plates more freedom of movement.

Hmmm, not sure I'm following his logic on that one, to me, when you incorporate a cutaway you take your recurve up into that area so as to retain the movement of the whole plate ( not so important where it's glued to the headblock obviously!), by leaving it thick and not putting any recurve in, would actually take movement away to my way of thinking.
Anywho, back to your original sketch with regards to the bit, I'm with Jeff, it would actually introduce vibration into the cut and could potentially spell disaster for the cutter and guitar should that lower section get bent slightly.
As for the binding on the Koentopp, thats the beauty of a pin router, the head is just for cutting and not following (thats what the pin on the deck's job is) so you could just set it to height and go around the whole body at the same height, it wont follow any top radius or differing thicknesses.

[blackalex1952]

Thanks Nick, re the recurve, fair comment unless he thins the edges there anyway...as for the shaft flexing, how about a 1/2 inch shaft?