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Rasp mark in slothead I'm building - Now fixed. Thanks.
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Author:  Colin North [ Tue Mar 25, 2014 10:55 am ]
Post subject:  Rasp mark in slothead I'm building - Now fixed. Thanks.
Title says it all.
Prevention is definitely better than cure....
Rasping the ramps in a slothead build and gouged the back of the slot slightly (about 1/16 - 3/32" deep and 1/4" wide).
Thinking to pare out the area with a chisel and use HHG to glue in a thick shaving from a spare part of the neck blank, then trim back.
Can anyone help me out with other suggestions?
Author:  Mike Collins [ Tue Mar 25, 2014 11:15 am ]
Post subject:  Re: Rasp mark in slothead I'm building
Colin;
I use a V.Speed Dremal with sanding drums.

No need to pare it out if your going to fill.
Then sand .
Mike
Author:  Michael.N. [ Tue Mar 25, 2014 1:47 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
That's quite severe. You really shouldn't be going that far into the slots. For that type of ramp I use a very short lifted stroke. The file or rasp doesn't go anywhere near the slot walls.
Be that as it may. You can graft a new piece of material on but you will need to flatten that area very carefully with a sharp chisel but the whole thing needs to be scooped. So you are approaching from both ends.
Author:  Colin North [ Tue Mar 25, 2014 2:25 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Thanks Michael and Mike.
The lighting is deliberately from a low angle to make the damage stand out, and looks a little bit worse than it actually is (although bad enough!)
Author:  Haans [ Tue Mar 25, 2014 3:30 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
If you have enough at the edges, you could make the slots larger. I've gone out to as close as 3/16".
Here's the hindsight solution. Works well, but you have to clamp the neck down solid and brace the drill so that you don't chatter over the overlay at the start. Rasp is 1/2" at the widest.

Image
Author:  Colin North [ Tue Mar 25, 2014 4:43 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Haans wrote:
If you have enough at the edges, you could make the slots larger. I've gone out to as close as 3/16".
Here's the hindsight solution. Works well, but you have to clamp the neck down solid and brace the drill so that you don't chatter over the overlay at the start. Rasp is 1/2" at the widest.

Image

Thanks for the tips Haans.
I'm at about 8 mm (0.31") and don't really feel like going through cutting the slots again. I did think about it, but not for long!
Author:  Trevor Gore [ Tue Mar 25, 2014 5:49 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
The simple answer is wider slots if you have the material to do it. I use some pretty narrow wall widths to get a straighter string pull. Pics on my website here. I rout the slots, so off-setting the router guide would work for me.

I've asked this one before, didn't get an answer, but will try again :D .

Does anyone have a neat jig that they'd like to share for machining the string ramps?
Author:  Haans [ Tue Mar 25, 2014 6:09 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
You have me thinking, Trevor. I can see sort of a "pocket hole" type clamp on jig with proper bits...wish I had a machine shop.
Author:  Terence Kennedy [ Tue Mar 25, 2014 8:19 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
I think about that every time I do a slothead. I'll think about it some more. I've been using that tapered Grobet rasp. I like that burr Haans.
Author:  cphanna [ Tue Mar 25, 2014 8:45 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
In terms of simplicity, ease, whatever you want to call it, I think Haans and Trevor have offered very good advice. Now...if I were in your shoes and I didn't feel that I had enough width on the side to affect that sort of fix, I would consider a graft that runs the full length of the slot. This is only because I think it would be easier to hide the starting and stopping points of my graft (at least for me), and I think it would be stronger than a small, partial graft. Much of what I have just written is based on my own instinct, so please don't mistake me for a repair expert. I'm not. That's just the way I would probably approach it after I got finished freaking out over the goof. (And I dare say everyone here has freaked out over a goof at one time or another. The great builders here just fix them and move on. I wish I could be equally confident!)
Author:  Imbler [ Tue Mar 25, 2014 9:13 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
I don't have a repair suggestion, but when I file the ramps with a round file, I tape strips of aluminum to each side of the slot to avoid gouges. It is quick and foolproof. You can cut thin gauge aluminum sheet easily on your bandsaw,
Mike
Author:  WaddyThomson [ Tue Mar 25, 2014 10:13 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Haans wrote:
You have me thinking, Trevor. I can see sort of a "pocket hole" type clamp on jig with proper bits...wish I had a machine shop.


Now there's a great idea! A pocket hole jig that registers in the slot, so no matter what the angle, it will be in line with the slot. Adjustable width type clamp with a thumb screw. Drill guide at proper angle for 5/8" drill
Author:  Tim L [ Wed Mar 26, 2014 12:58 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Wonder if you could attach a long slug to a bit and use that as a guide for your ramps.
Thinking along the lines of a pattern bit and replace the bearing with long slug. Preferably a slug that had internal bearings so it doesn't burn the inside of the slots.
Author:  Michael.N. [ Wed Mar 26, 2014 1:05 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Maybe you are all over thinking this. They are two little ramps that take a few minutes with a pointy rasp. I fail to see the difficulty or the time sink.
Author:  Colin North [ Wed Mar 26, 2014 2:38 pm ]
Post subject:  Re: Rasp mark in slothead I'm building
Glue pot warmed up, went for it.
Author:  Colin North [ Wed Mar 26, 2014 2:44 pm ]
Post subject:  Re: Rasp mark in slothead I'm building - Now repaired
Thanks to all for the suggestions with the fix..
And I agree a bit with Mr N., even if he did tell me off.....
Author:  RusRob [ Wed Mar 26, 2014 4:39 pm ]
Post subject:  Re: Rasp mark in slothead I'm building - Now fixed. Thanks.
That is a beautiful looking repair there Colin,

[:Y:]
Author:  Trevor Gore [ Wed Mar 26, 2014 5:34 pm ]
Post subject:  Re: Rasp mark in slothead I'm building - Now fixed. Thanks.
Nice work, Colin!

Michael.N. wrote:
Maybe you are all over thinking this. They are two little ramps that take a few minutes with a pointy rasp. I fail to see the difficulty or the time sink.

I prefer the flat ramps (Panormo-esque) to the rasp ramps. Tough to do in less than half an hour, even with a custom made chisel. Maybe I should just rig a shoulder plane to the exact size of the slots and go at it that way.
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