Official Luthiers Forum!
http://www.luthiersforum.com/forum/

routing out backstrip
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=23078		 Page 1 of 1
Author:  P@uL [ Tue Jul 14, 2009 10:16 am ]
Post subject:  routing out backstrip
hey everyone was gonna put together a luthiers shooting board today. but then i started thinking. the shooting board is great for joining the back and top. but how do you guys cut the slot for the backstrip?

this is a rough mspaint drawing of what we used in my course. it was used for joining the tops and back as well as routing out the backstrip with a router.

Image

basically its a base then two boards attached on top to create an open space for the router to get through. and a board on top clamping down your back or top with threaded rod and wing nuts. just wondering if anyone has used something like this and or has a better method. looking for simple small jigs since i am limited to space already with all the new shelving and island bench i just put up.
Author:  Mike Collins [ Tue Jul 14, 2009 11:45 am ]
Post subject:  Re: routing out backstrip
P@ul;
If it's easy to set up and does a great job then you have a winner there.
I use a straight edge to guide a router -right to left -.
I use many different back strips and this is easy to set up.
I use the same router all the time so I know what the distance from the center of the bit to the outside of the base is.

Mike
Author:  P@uL [ Tue Jul 14, 2009 5:59 pm ]
Post subject:  Re: routing out backstrip
holy its just that easy. i never even though of just lining up a straight edge and running a router/dremel down it. its the same thing minus the elaborate jig/work board. i already built my manual shooting board today anyway so good answer! kinda feel dumb that i couldn't think of that before... duh
Author:  peterm [ Tue Jul 14, 2009 6:08 pm ]
Post subject:  Re: routing out backstrip
I just glue in whatever I want in the center as I join the backs. No need to route at all.... just sand flush.
Author:  meddlingfool [ Tue Jul 14, 2009 6:39 pm ]
Post subject:  Re: routing out backstrip
I find using the straight edge that the router wants to drift. Which is fine as long as you make sure the straight edge is on the side the router wants to drift to. I push the router away from me with the straight edge on the left. A little bit of pressure against the fence keeps it tracking nicely.
Author:  P@uL [ Wed Jul 15, 2009 9:57 am ]
Post subject:  Re: routing out backstrip
peterm wrote:
I just glue in whatever I want in the center as I join the backs. No need to route at all.... just sand flush.


that's interesting. are you thicknessing your back down before gluing? how do you deal with the fact that most binding/purfling used for that isn't as thick as your back is going to be?
Author:  peterm [ Wed Jul 15, 2009 10:48 am ]
Post subject:  Re: routing out backstrip
I finish my backs at about .095" and make sure the purflings are tall enough. I press them down and sand after the join is dry. Its the easiest way and you don't have to worry about accuracy to the center 'cause it will be in the center. ;)
Author:  Stefan [ Wed Jul 15, 2009 10:55 am ]
Post subject:  Re: routing out backstrip
peterm wrote:
I just glue in whatever I want in the center as I join the backs. No need to route at all.... just sand flush.


I've done this with my two backs I've glued up (one guitar built out of that). I used a jointer to get the edges of the back as strait as possible, then a couple of passes with a plane. The strip came from lmii and seemed pretty strait, so in it went. No problems yet.

But this is a little different than say jointing the top (or back if you didn't have a filler strip). Planing both edges on the shooting board simultaneously then using the candling technique to check the perfection of the joint. You can't do this simultaneous planing of edges and candling with the filler strip and the back joints, or can you?

Stefan
Author:  peterm [ Wed Jul 15, 2009 12:01 pm ]
Post subject:  Re: routing out backstrip
You have to prepare the backs the same way you'd do it even if there was no backstrip of some sort. That means having a perfect jointed seam.
Author:  Kennyboy [ Wed Jul 15, 2009 12:27 pm ]
Post subject:  Re: routing out backstrip
The easiest method ,is running a laminate trimmer along a straight edge, obviously measuring must be dead on, and run your router on the right side of the straight edge, this will cause the rotation of the router to keep you tight against the straight edge (counterclockwise rotation will move toward the straight edge) clamp your straight edge in place , or use good double sided tape, keeping the straight edge parallel to your centerline. good luck
P.S. try using downcut spiral bit, leaves a very clean slot
Author:  Kennyboy [ Wed Jul 15, 2009 1:38 pm ]
Post subject:  Re: routing out backstrip
peterm wrote:
You have to prepare the backs the same way you'd do it even if there was no backstrip of some sort. That means having a perfect jointed seam.

so you can see the backstrip, through the sound hole ?sounds interesting.
Author:  Bob Long [ Wed Jul 15, 2009 2:44 pm ]
Post subject:  Re: routing out backstrip
meddlingfool wrote:
I find using the straight edge that the router wants to drift. Which is fine as long as you make sure the straight edge is on the side the router wants to drift to. I push the router away from me with the straight edge on the left. A little bit of pressure against the fence keeps it tracking nicely.

If I understand what you're saying... the reason you are having drift is you are running the router against the wrong side of the guide. If you're pushing the router away from you, the guide should be on your right.

long
Author:  mateo4x4 [ Wed Jul 15, 2009 5:30 pm ]
Post subject:  Re: routing out backstrip
Kennyboy wrote:
peterm wrote:
You have to prepare the backs the same way you'd do it even if there was no backstrip of some sort. That means having a perfect jointed seam.

so you can see the backstrip, through the sound hole ?sounds interesting.



Yes and no. Most folks do a brace/patch down the center line on the inside of the back for added strength/support. This will cover the lam'd in center strip.

-Matthew
Author:  peterm [ Wed Jul 15, 2009 5:38 pm ]
Post subject:  Re: routing out backstrip
You still have to glue in a center reinforcement patch on the inside.
Author:  Dave_E [ Wed Jul 15, 2009 6:34 pm ]
Post subject:  Re: routing out backstrip
My classical builds all did the center strip between the halves during assembly. Just the way Sloan's book said to do it (that was 15 years ago). I don't think strength is an issue either way, but I'd put money on the routed strip method being stronger.

Dave
Author:  Chris Paulick [ Wed Jul 15, 2009 6:40 pm ]
Post subject:  Re: routing out backstrip
My first build was a martin kit and the back strip was glued between the back plates. That's nothing new and works as long as you know what you want for a back strip and can make it thick enough. Pearl and recon stone and the such would have to be inlaid.
On the edge think of it as how the router is turning. Clockwise when viewed from above(normal motor rotation is clockwise when view from the back and not the shaft end) so when you are cutting into the wood the counter force of the router will be counterclockwise so it will torque the router that direction. So yes if you arepushing the router away from you then edge to the right. If routing left to right then the edge between you and the router. Note that is only when you are routing in an unrouted surface. If say you routed a grove and it needed opened and you moved the edge guide to the right then you don't want to feed the router away from as it would be climb milling and it will grab and possibly pull out of your hand so you would want to route towards you. You can climb route but you only want to remove a little material and have a really good grip. The only time I climb is when cleaning up an already routed piece and when routing binding channel and I'm always cautious with a good grip and try taking a couple of pass if need be. When ever routing you need to be aware of the rotation of the router and whether or not you are climb mill or not. Once you have a piece of wood fly out of your hand or the router pull on you , well it's a scary thing to say the least.
Author:  meddlingfool [ Wed Jul 15, 2009 6:51 pm ]
Post subject:  Re: routing out backstrip
Bob Long wrote:
meddlingfool wrote:
I find using the straight edge that the router wants to drift. Which is fine as long as you make sure the straight edge is on the side the router wants to drift to. I push the router away from me with the straight edge on the left. A little bit of pressure against the fence keeps it tracking nicely.

If I understand what you're saying... the reason you are having drift is you are running the router against the wrong side of the guide. If you're pushing the router away from you, the guide should be on your right.

long

Hmm. Two voices contrary. I use the technique I described without failure so far, however, I think I shall load up a piece of scrap and try your way. Nothing beats finding out for sure!
Author:  Chris Paulick [ Wed Jul 15, 2009 7:37 pm ]
Post subject:  Re: routing out backstrip
I guess you haven't watched my videos? :) I tried to explain it some what in this one. It would have been easier to say keep the guide or template to the right og the direction of travel but I never thought of that until reading this discussion. But keep in mind that's in an unrouted surface.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/