Official Luthiers Forum!

I've got one but haven't been getting good results. There's no consistency from end-to-end or side-to-side.

One end will be fine, but the other end will be thicker. Not only that, but the thicker end will be different thicknesses on each edge, and the apex of the arc will be off-center.

Before sanding, I've made sure my uprights are plumb and that the center line of my board is lined up with the center line of my cross beam.

Here was my methodology tonight:

- adjusted pivot point to desired radius
- hung swing arm on support arms and adjusted so that bar could swing freely
- started lowering the swing arm to the belt using the fine adjustment screws. This part was decidedly more difficult than it should have been. As I swung the bar, the screws would work themselves down so that too much of the board was contacting the sander. I had to keep my hands on the screws while trying to swing the bar back and forth.

Here are a couple pics of what I'm getting.

This end looks pretty good. Maybe slight thickness variations on each edge.



But this end is pretty bad. Different thickness on each edge, and arc apex off-center. Also, this end is thicker than the other end.


Has anyone had issues when first using theirs, and if so, do you have any tips or tricks? I've been fighting with getting a jig set up for 3 months now (one home-made version and now this one), and I've pretty much had my fill.

And please, for the sake of my already-tenuous sanity, please don't recommend a different radius jig or tell me how easy it is to sand by hand. I've been building that way for 4 years now.

Thanks, all.

I had problems with my (different style) jig flexing, which caused inconsistent results. Even the slightest downward pressure or racking could do this. If your jig is sturdy, then the mounting surface and belt might not be parallel. Is the radius of each side exactly identical?

I haven't been terribly impressed by it, but it did work through a group of fingerboards on the jig with a group of fellow students. The most common problem I saw was not letting the sandpaper do its work. It seemed to need the patience to swing the fingerboard at the end of the process with little to no pressure over and over again until you heard virtually no scraping or sanding sound to get a smooth and accurate radius.


Sent from my iPhone using Tapatalk

Yeah, my home-made version had way too much flex, so I scrapped it after trying to rig it for 2 months. Then I got this one thinking it would cure all my ills.

No, the radius on each end is slightly different. One end will be my desired radius, and the other will be tighter. I'm going to take the belt off tonight and take some good measurements to see exactly where everything is in relationship to everything else.




I've got another builder friend who has the jig, and he gets great results from his. I called him last night, and there were some process things I was neglecting. After I take my measurements tonight and make sure everything is set up dead-on, I'm going to follow some of the procedures he filled me in on. Hopefully I'll have a better process tuned up by the weekend.

This post has been deleted.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

Tim, that is slick!

_________________
Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

Where do you get a 16" radius bit?

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

This post has been deleted.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

Please share what those processes were and I will pass them along to the school. Any help on using the jig will surely be appreciated.

Whenever I buy a jig to solve a problem, I re-learn that 10% of solving the problem is the right jig and 90% is how you use the jig.

Have you asked Grizzly for suggestions? They may be able to offer some guidance.

Whenever I've contacted Grizzly for help with their products they've responded. Couldn't hurt to ask.

_________________
Tim Allen
"Never hurry, never rest."

After contacting Grizzly, we figured out that the cross member wasn't quite centered, so I had to loosen those allen bolts and correct that. I then made sure my support arms were plumb in both directions. Turns out one of them was pretty far out.

Once those issues were addressed, I made sure I had a perfect center line marked on my cross member and fretboard.

I attached the fretboard and adjusted the pivot points to my desired radius. Then I put pencil marks on the fretboard. When lowering the board onto the sanding belt, you want to make sure it's hitting both ends equally, and the pencil marks help to ensure that's happening. Once I've got that part worked out, it's simply a matter of swinging the arm. You need to take it fairly slowly, though.


You nailed it, Tim. Yes, I sent Grizzly an email, and they were very helpful in helping to solve some of the issues, and once I implemented proper procedures for using the jig, things came together nicely.

Thanks! I'll pass those tips on.


Sent from my iPad using Tapatalk