stuck bow frog slide

[Mat Roop]

I have a student bow with a slide that is stuck in the frog...I have rehaired maybe a hundred of bows, but this is the first I cannot get the slide out of the frog... I use high tack masking tape rolled up with tack outside to push out a slide... but this one won't budge.... It must have some glue in the slide mortise.

I am tempted to not bother, but I love a challenge, and maybe I can learn from this in the event this happens with a good bow.

Any ideas of what might work?

Thnaks, Mat

[GMM22]

You need impact force rather than continuous force to break the bond. Apply double sided tape to a popsicle stick narrowed for a portion to the width of the slider. Apply to the slider (make sure the surface mating area is large) with the long end behind the frog which is held in a bench vice (with leather jaws of course), and tap the end of the stick in the slider exiting direction with a mini hammer or block of wood. Think fast moderate blows rather than heavy blows, and keep a thumb pressing down on the slider.

This will remove most stuck sliders, but I have seen the odd one that was almost certainly glued in, for which there is little cure but to carve it out and install a new one.

Caution: Once it is loosened, you must be careful as you now have a long stick connected to the slider that acts as a lever, and a small amount of lateral force will break the v grooves. Carefully remove the slider from the frog and then remove the slider from the stick.

[krugwaffle]

Lots of luck to you Matt. The first and only frog I've ever taken apart was glued together with superglue. I thought it was just me and I was too stupid to figure out even the simplest puzzle. I began to suspect something was wrong when the ferrule came off after much effort leaving behind a residue of some sort on the ebony.

I ended up extracting the slide by applying a lot of solvents and a lot of heat. I would soak the hair with acetone and it would wick into the frog. I then heated the whole thing with a heat gun and worked the slide trying to get it to move. Once it did start moving, it had to be forced all the way off as the glue had completely fouled the slots. Next I had to dig all the old hair out, virtually re-carving the mortice as I went. The superglue had wicked into the hair, solidifying it and the plug into a hard plastic mass.

Evidently, I did a fairly good job. I sent all the pieces in to the repair shop and they were able to rehair the bow using the same frog, slide and ferrule. My interest in this wasn't the desire to learn rehairing or bow repair but to just find out what was wrong with the frog. It was a cheap bow and I didn't really care if I fixed the frog or not. I now know what's inside a frog and that's good enough for me.

[fiddlecollector]

Dont know what sort of bow it is ,but make sure its not the old French style where the slide is one piece right to the back of the heel.i.e the pearl and small heel plate are both fixed to the slip of wood.

[DonLeister]

Try pressing on the slide with a fat rubber band and pulling like you would normally.

Unfortunately some slides are glued in, a soak in acetone can sometimes get it unglued.

Good luck!

[Brad Dorsey]

I can get most stuck slides out with rolled masking tape just as you tried. If that doesn't work, next I heat the frog under a light bulb for about five minutes to soften any glue or rosin and try the tape again. In the very rare cases where the heat doesn't work, the next step depends on the quality of the bow. On cheap bows, I try forcing a small chisel blade between the slide and the heel plate. If this doesn't work, I decide the bow is not worth rehairing and give up. Because it damages the heel plate, the chisel method is unacceptable on a good bow, , so I remove the slide by destroying it and fit a new one. In thousands of rehairs, I've only had to do this once.

[chrisandcello]

I've only had course to use anti slip matting under thumb pressure and sometimes a blade or small pliers to get the initial movement.....good luck

[Brad Dorsey]

After writing my previous message I went to rehair a bow, and, sure enough, the slide was stuck. The tape didn't work. The heat separated the pearl from the ebony liner. The pearl slid out, but the liner remained securely stuck. I destroyed the liner, took it out in pieces and cleaned out the slide channel. Then I glued the original pearl onto a new ebony liner. It works out like this occasionally.

[GMM22]

Hmmm... There is an interesting and apparently unkown option on the table now. I might have thought one would take the opportunity to put it to the test

[Mat Roop]

Thanks everyone for the great tips...I had not thought of the double sided tape and tapping with a tack hammer...tried that and presto the mother of pearl slide came out clean but left the ebony underslide in place. Not having any acetone to try the soaking idea... I cut the underslide in half, pulled it out in pieces. It was glued with some sort of white rubbery goo....the goo was used excessively to glue the mortise wedge but got into the slide channel. Anyway, made a new ebony underslide in no time and reglued the mother of pearl on top and it is like the original with no damage at all.

Cheers, Mat

[GMM22]

That's good. The DS tape is usually effective at initiating movement in sliders, except where the bond between the ebony underslide and the channel is greater than the bond between the shell and underslide. It is less invasive than chemicals, chisels, or heat.

[Mat Roop]

GM22... must say the more I think of it the more I like your method. One of the problems I have had with the rolled tape (and likely also the friction matting or elastic band) is that sometime it is necessary to apply a lot of downward pressure on the frog to get the grip and I have had damage to the delicate bottom edges of the frog.... even though it was supported in its normal position on a bow. In this case it took very little pressure and light tapping to release the pearl... have you thought of a patent?

Cheers, Mat

[GMM22]

Ah yes, I can read the headlines in the NY Times business section: Luthier stuns bowmaking world with advanced slider removal process. Licensing fees net seven figure revenues in first quarter.

[GMM22]

The other advantage (besides less downward pressing force on the slider) is the way the force is applied. Instantaneous force of impact is much more effective at breaking the frictional bond that prevents initial motion.

[Brad Dorsey]

"One of the problems I have had with the rolled tape (and likely also the friction matting or elastic band) is that sometime it is necessary to apply a lot of downward pressure on the frog to get the grip and I have had damage to the delicate bottom edges of the frog"

That you have this problem tells me that you do not have a proper frog holder. The frog holder needs to: 1. Hold the frog upright without clamping it; 2. Support the frog on the bottom center facet, not the delicate bottom edges; and 3. Have clearance for the eyelet. With these conditions met, the frog can be safely worked on without damaging it or the stick. I'll try to put up some pictures of my frog holder.

[Mat Roop]

quote:

---

Originally posted by:

Brad_Dorsey

I'll try to put up some pictures of my frog holder.

---

Brad... that would be greatly appreciated!... Mat

[Brad Dorsey]

This frog holder is sized to take violin, viola and cello bow frogs. I have a bigger one for bass bow frogs.

[GMM22]

The clearance for the edges is good, but I am confused as to how you keep the frog from moving around while working on it. Perhaps you simply have good technique. I need the frog protected and secured in place.

Below is a picture of my clamp, which is similar in function at the bottom, but it also has an adjustable jaw. The leather pads clear the delicate edges and only clamp the frog at mid section. It takes a bit of effort to make, but then again, you only have to make one.

The knurled thumbscrews provide a greater tactile response to reduce the risk of over clamping. This system also provides some surrounding flat surface area from which to gain auxiliary leverage and stability for the hands.

[Brad Dorsey]

"I am confused as to how you keep the frog from moving around while working on it."

You are correct that the frog has a little wiggle room in my holder, but I never find myself handicapped by this or feel the need to have the frog clamped rigidly. Generally, I hold the frog and holder with one hand while the other hand manipulates a tool (chisel, file, etc). The eyelet, when it is present, keeps the frog from sliding lengthwise, but the absence of the eyelet does not present a serious difficulty.

To me, your frog holder looks unnecessarily complex. And although the clamping surfaces are well-padded with cork, I think they would be safer if they were more convex to match the shape of the sides of a frog.

[GMM22]

Complex? Perhaps, but not inordinately. The clamping surfaces are leather, not cork, and fit the contour perfectly due to the lip clearances (which are not easily seen in the picture) and the way thick leather conforms to curved surfaces. There is not even a remote possibility danger. One of the advantages of complex jigs and fixtures is that they are a product of design concepts that consider every possible risk factor.

Keep in mind I was not being critical of your holder, as it obviously works successfully for you, but for those who need greater stability, my version will offer some advantage.

[Brad Dorsey]

"Keep in mind I was not being critical of your holder, as it obviously works successfully for you"

Same here.

[JCHungerpiller]

GMM22

I just used your double sided tape for a stuck frog. It worked very nicely. Thanks...you saved me some grief.

John

PS: I hope you get this...I tried to send via private but it is turned off or not working.

[apartmentluthier]

fiddlecollector,

Do you have any pics of the "old French style" that you mentioned in this thread?

[welshman]

Hi GMM2,

I too got a chance to use your double faced tape idea, it worked like a charm and not chipped edges on the pearl too, I had a roll of photo mounting tape so I used that and a small narrow piece of wood that I will now save for just this job. I was able to hold the frog against my block of wood with the hold in it for the eyelet and gave the end of the stick a tap with my small adjusting hammer and it popped loose.

I always give the side of the slide and the groves in the frog a good coat of pencil lead just to avoid this problem.

It looks like the surface area tension is enough to break the stuck slide loose, great technique. thanks

Reese

[Brad Dorsey]

...Do you have any pics of the "old French style" that you mentioned in this thread?

Here's one. Notice that part of the silver heel plate is part of the slide and comes out with the pearl when the slide is removed. If you thought this was a normal slide and you tried to remove it by inserting a sharp tool between the pearl and the silver, you would damage it.

"