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| fret slotting - how to be perfectly square http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=33699 |
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| Author: | Tai Fu [ Wed Sep 28, 2011 1:47 pm ] |
| Post subject: | fret slotting - how to be perfectly square |
This is my slotting setup now... it's fully portable since it will go back to Taiwan with me. I have a stewmac fret saw, a fretboard (I need to slot it now because it cracked during transit, might as well use this one as practice. I use a block of wood and clamp to secure the fretboard, but the problem I run into is that sometimes the cut isn't exactly square (it's off by about half a saw kerf), because the slot in the miter box is much wider than the saw. So can anyone tell me if the frets are slightly off square will it hurt things? I noticed the fretsaw isn't exactly flat either, it's bent by about .001 or so. |
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| Author: | Rod True [ Wed Sep 28, 2011 2:16 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Yes it will matter. I'd never trust a commercially bought miter box like that. It's square enough for cutting door moldings....but You can use a machinist square then clamp a block of planed wood at the fret location to get the bearing edge for you saw, I did this on my first 4 guitars and they are all still working fine. |
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| Author: | J.L.K. Vesa [ Wed Sep 28, 2011 2:29 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
well, if every fret is off square by exactly same amount, and they are located at right places, it will not be a flaw, it will be a feature, and you can call it slanted frets ala Jeff Traugott: http://www.tunesbaby.com/yt/?x=ROi-qFEX1vk |
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| Author: | Michael.N. [ Wed Sep 28, 2011 2:55 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
My method is relatively simple and tool poor. Some years ago I made a fretscale rule (in wood) that has 4 scale lengths. Each 'fret mark' is actually a very shallow and very fine saw cut. This is clamped to the blank board, a knife blade is located in each of these 'fret marks' and I put a tiny nick in the board for each division. It's much faster than trying to read from a Ruler. Dispense with the wooden fret rule. Locate the knife in the first 'nick', push an engineers square right against the knife. dispense with the knife and push your fretsaw against the square. I tilt the square up a touch to avoid the set of the saw teeth. Cut the first fret position and continue in the same manner for the rest. It works very well and is pretty quick. Seems to me that it's much quicker than the hand fret mitre boxes from S.mac and LMI. Of course it relies heavily on the accuracy of my home made fret rule - which is why it took me the best part of 10 hours to make. Looking through magnifiers for long periods of time and checking each and every fret position 20 times isn't my idea of fun. |
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| Author: | Tai Fu [ Wed Sep 28, 2011 3:01 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
I had just realized something... I think those fret saws are designed to be used with a depth stop or something, so without it the blade isn't completely flat... since the steel is springy. I think I need to make a stiffener for the saw and epoxy them to both sides of the saw, maybe just enough that it fills the slot on the miter box completely. |
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| Author: | mcgr40 [ Wed Sep 28, 2011 3:19 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
use your machinist square to layout a new slot and cut it with the same saw you want the kerf to fit. That will remove the play. You can make any number of small jigs for sawing funny miters like, too. |
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| Author: | Tai Fu [ Wed Sep 28, 2011 3:38 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
mcgr40 wrote: use your machinist square to layout a new slot and cut it with the same saw you want the kerf to fit. That will remove the play. You can make any number of small jigs for sawing funny miters like, too. Problem is, the saw isn't meant for cutting through such thick wood... normal miter saws have a set so that the kerf is always wider than the saw blade itself. I think if anything I might be able to widen the slot (with a router or something) to accommodate a depth stop. |
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| Author: | Michael.N. [ Wed Sep 28, 2011 4:14 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
If that is the Stewmac or LMI fret saw it's pretty much a standard Gents saw, just a bit longer. Nothing special about it. It shouldn't need anything to keep the blade straight. I don't use the saw with any mitre box and it cuts straight slots. Check the Brass back and see if that is straight, otherwise your blade may have a kink in it. |
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| Author: | Tai Fu [ Wed Sep 28, 2011 4:40 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Michael.N. wrote: If that is the Stewmac or LMI fret saw it's pretty much a standard Gents saw, just a bit longer. Nothing special about it. It shouldn't need anything to keep the blade straight. I don't use the saw with any mitre box and it cuts straight slots. Check the Brass back and see if that is straight, otherwise your blade may have a kink in it. Well the brass back is straight, and the blade itself has a very slight bend to it. I found a way to solve the squareness problem. First I mark out the fret slot position on a template, another guitar, etc. with a knife. Then I use a machinist square and draw the lines out, and compare it with the original to make sure its right. Then I carefully put the saw against one side of the slot, and slowly start the cut in pull stroke only. When the cut is started I clamp the piece down, and then continue cutting until I reach the desired depth... It takes forever but it works. I am going to add an integrated clamping mechanism to this miter box to make this thing easier to use later on. Now I gotta add a Dick number 6 plane to the luggage I am taking back to Taiwan, because it's hard to get decent planes there. Nothing like planes in a plane... |
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| Author: | Tai Fu [ Thu Sep 29, 2011 12:50 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
by the way, when I start cutting the slot, at first it was very easy, but as the slot got deeper it started dragging and at some point it was impossible to pull the saw through unless I took it out of the slot, and then put it back in. I wish there is an easier way to cut this slot, because of the dragging I am finding that it takes all day to slot an entire fingerboard! |
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| Author: | Dave Stewart [ Thu Sep 29, 2011 1:32 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
This is the way I've done it on quite a few. After scoring the marks, position the square and clamp, draw the (carefully squared and sized) block up to sandwich the sawblade snuggly and clamp, and saw with blade pressed against block 'till the saw back "bottoms" on the top of the block (for correct depth). The saw shouldn't "bind" as you go deeper...something not right. |
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| Author: | Tai Fu [ Thu Sep 29, 2011 1:44 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Dave Stewart wrote: This is the way I've done it on quite a few. After scoring the marks, position the square and clamp, draw the (carefully squared and sized) block up to sandwich the sawblade snuggly and clamp, and saw with blade pressed against block 'till the saw back "bottoms" on the top of the block (for correct depth). The saw shouldn't "bind" as you go deeper...something not right. WOW! I took your advise and sandwiched the saw blade like you suggested, using one edge of the miter slot as a wall and then another block of wood (I will make a properly sized one as soon as I get some shop equipments in Taiwan...) and what a difference, significantly less binding, although there are some resistance its not nearly as bad anymore. The saw blade isn't so straight (but the spline is) so I think the sandwiching straightens the blade eliminating the binding. thanks for your advise! |
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| Author: | Michael.N. [ Thu Sep 29, 2011 1:46 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
The saw needs sharpening. It shouldn't bind in the cut, at least not when it's cutting the depth of a fret. It takes me around 10 minutes (maybe less) to cut all the slots with my LMI saw. That's after I sharpened it. It certainly didn't cut that way when it was new  Nor should it need to be clamped both sides. In fact it shouldn't need to be clamped at all. |
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| Author: | Tai Fu [ Thu Sep 29, 2011 2:07 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Michael.N. wrote: The saw needs sharpening. It shouldn't bind in the cut, at least not when it's cutting the depth of a fret. It takes me around 10 minutes (maybe less) to cut all the slots with my LMI saw. That's after I sharpened it. It certainly didn't cut that way when it was new Nor should it need to be clamped both sides. In fact it shouldn't need to be clamped at all. The saw wasn't straight to begin with, since it was designed to be used with a depth stop which stiffens it... the blade itself isn't stiff enough to hold a straight line, thus the need to clamp it. I have no idea how to sharpen a saw, because the teeth is fairly small and I don't have stones or files small enough to get at each teeth.... |
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| Author: | Michael.N. [ Thu Sep 29, 2011 2:19 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Which saw is it? |
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| Author: | Tai Fu [ Thu Sep 29, 2011 2:20 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
Michael.N. wrote: Which saw is it? Stewmac |
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| Author: | Michael.N. [ Thu Sep 29, 2011 2:35 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
I doubt that there is anything special about that saw. The Saw is made by Thomas Flinn in England, of around 0.5mm gauge. I have much deeper dovetail saws than that, made of the same gauge. They don't need anything to keep them stiff. They can all be easily bent between finger and thumb. Forget the idea that it needs a mitre box to work. It doesn't. My guess is that you have a perfectly good saw but it is a little blunt. Just like mine was when it arrived. My saw went from Sheffield, all the way across the Atlantic and back to Sheffield + 40 miles!! That too would not cut a fret slot without binding. I gave up on it. Then one day I had the idea that I had nothing to lose if I tried to sharpen it. It certainly wasn't being used. All I really did was a quick stroke on each tooth. It transformed the saw. The difference was night and day, as they say. That's the trouble with England these days. Only two saw makers left and no one who can sharpen. |
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| Author: | Ian Cunningham [ Thu Sep 29, 2011 8:12 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
After buying the stewmac fret saw, I find that my little flush cut japanese saw I got for next to nothing works better for cutting fret slots than that thing. I lay it up against a combination square frame. Works alright. |
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| Author: | unkabob [ Thu Sep 29, 2011 9:08 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
My approach is to build a miter-box to fit the fretboard blank width exactly. I build one for each scale-length and lay out each fret exactly cutting the slots using my fretwire saw. I include a zero-fret-slot and when that is cut, I drill on the centerline in the slot for a brad to hold the blank in place for the rest of the slots and for gluing to the neck. This arrangement fits the blank width and saw-cut width and fret squareness but has no control on slot depth. Bob 
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| Author: | TonyKarol [ Fri Sep 30, 2011 3:45 pm ] |
| Post subject: | Re: fret slotting - how to be perfectly square |
I ran into Dave Stewart today out at a wood shop .. we chatted briefly about slotting FBs .... IMO, slotting the FB square, when you have an untapered board isnt really that important .. what is important to have the slots square when the FB is all done, is the next step, which requires you to taper the FB such that the slots remain square to the centreline !!! So, if your technique for tapering is lousy, no matter how good you are at keeping the slots square in the blank, it wont matter in the long run. If your mitre box is slightly off, you can compensate by making sure you taper evenly on each side, once establishing a line square to the slots down the centre of the blank and measuring from that. Or, get a table saw, and a CNC'd template .. 
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