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 Post subject: Mini pin router
PostPosted: Tue Jul 06, 2010 5:43 am 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
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Can't remember if it was asked here or on the guitar thread, but here's my new pin router for ff holes.

viewtopic.php?f=10101&t=28091


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 Post subject: Re: Mini pin router
PostPosted: Tue Jul 06, 2010 10:33 am 
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Koa
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you must view the proxxon video... wait for it... nearly the last phrase spoken in the video. '... just unpack the ...' :lol:
http://www.proxxon.com/eng/html/28500.html

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 Post subject: Re: Mini pin router
PostPosted: Tue Jul 06, 2010 10:17 pm 
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Koa
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Hans,
Thanks for the heads-up on the proxxon.

Have you always bound your F tops before glue-up?

Image

Also, do you bind it completely and then sand it flush with underside of top... like on a big sanding board?
thanks,
chris

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 Post subject: Re: Mini pin router
PostPosted: Tue Jul 06, 2010 10:20 pm 
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Koa
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Hans,
Your top shape and size, and, rim would really have to be spot on for this to work... what am I missing here?
chris

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 Post subject: Re: Mini pin router
PostPosted: Sun Jul 11, 2010 11:05 am 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
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Well Chris, good eye. I've built over 250 mandolins this way and never told a soul. This is what I do. Build the ribs and when you have the top or back roughed out, tack glue it onto the rim. Rout to the inside of the binding and to any depth...like 1/8" or so. Remove the top, draw in the scroll cutout and cut (bandsaw) close to the rout, then true it up with a drum sander or OSS, and files in the small areas around the scroll. Bind the top or back. Sand off the inside flush with a DA. Finish carving the top or back and graduate, cut ff holes, add tone bars etc. Glue it on the rim.
This all has to be done very carefully, but it works.


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 Post subject: Re: Mini pin router
PostPosted: Mon Aug 02, 2010 9:20 am 
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Cocobolo
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Hanns,

Having purchased one of the Proxxon rigs I'm getting it ready to become a pin router in pretty much the same way as you described here. Now that I've got the Proxxon a few questions arise:

- the head is not keyed in any way on the shaft so I'm assuming one has to set it low enough to clear the top plate and centered on the base pin

- However, the Proxxon vertical spring-loaded head doesn't have a stop for the head to hold it down. How are you holding the head in the down position?

I don't think you can just loosen the clamp on the rear column and slide the whole thing down because you would lose the center on your base pin. I can see that you might make a clamp for the rear column that rides on top of the head so you could lower it with the spring loaded lever and then tighten the clamp to hold it down.

Just wondering what you did before I start making any decisions or modifications. Oh, and by the bye, the rear vertical shaft and the hole for holding the tool are not 3/4" as was mentioned somewhere, it is metric and a tad larger than 3/4. This is important if you are going to make an adapter to hold the tool as I plan to. I may use a B&D RTX or adapt it to hold a handpiece since I don't have a Proxxon rotary tool.

A related question that also refers to your thread on alternative ways of building and binding before gluing the plates. Any reason you can see why one couldn't make a pin router template that is 0.090" (or whatever binding width is) smaller than the outside profile and use that to trim off the sides of the plate for binding? This assumes that the body mold and the tops are pretty consistent, but if so do you see any problems?

Alan D.


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 Post subject: Re: Mini pin router
PostPosted: Tue Aug 03, 2010 6:44 am 
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Brazilian Rosewood
Brazilian Rosewood

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Alan, there is a screw somewhere around the rear end of the unit (if I remember right it is near where the spring is) that regulates the amount of drag you can put on it to make it hard to pull down, and will at some setting hold the unit where you put it. I made no mods to the drill press...
I never could with any accuracy make the ribs come out the same for any 2 instruments (got to be pretty dang accurate for that to work) so I decided to rout to the shape that the ribs were.


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 Post subject: Re: Mini pin router
PostPosted: Tue Aug 03, 2010 9:54 am 
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Koa
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Alan,
Like Hans wrote, there is screw to tighten the action. On my unit there is an set screw on the left side that you can tighten to pinch the unit in place. I just pull the bit down and tighten the screw a bit to hold it in place. I had thought of making a collar(with a thumb screw through it) that fits around the shaft to hold it down as well, but the screw on the left side has been working fine for me so far.

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 Post subject: Re: Mini pin router
PostPosted: Tue Aug 03, 2010 10:56 am 
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Cocobolo
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Many thanks guys. I'll check out the set screw thing and maybe just turn it into a knob for easy access. Hanns, makes sense on the binding, even a little bit out and it would really show.

Alan D.


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 Post subject: Re: Mini pin router
PostPosted: Tue Aug 03, 2010 11:17 am 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
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Sure Alan, you don't have to tighten it down to a stop. Little at a time and you can find a point where it will stay down, but you can move it up and down with the handle.


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 Post subject: Re: Mini pin router
PostPosted: Thu Nov 04, 2010 1:30 pm 
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Cocobolo
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I thought I'd revive this thread since I finally got around to completing a couple tops to the F-hole stage.

A couple things to remember:
- always make sure that the depth stop is set so it can't go lower than the pin. I was doing a test with scrap and the up-cut spiral milling bit pulled itself and the router rig downward and pushed and milled the pin right into the table. Of course this meant that the router bit was now following the pattern template with the obvious results. So why do we always test with scrap?
-- the fix is of course to set the stop. Further I made a piece of PVC pipe that I dropped down on the large shaft in the back so it can never go below that. 5-minute epoxy makes a nice repair to poly-carb template :?

- The screw to apply clamping pressure on the slider part only engaged about two threads. When I tried to tighten it it stripped out. I needed to purchase a longer M4 screw to get at more of the threads. Then it can be easily adjusted to snug the slider part.

- The clamp at the back that adjusts the overall height is fine for the intended drill press use, but almost inadequate for a pin router application. The issue is not vertical but rotational clamping. Since the lever arm from the shaft at the back to the mill at the front is rather long it was/is easy to bump it and make it lose it's position over the pin. For the time being I just really clamped it down.
-- the real fix would be to grind a flat on the rear shaft and then get a set screw into the slider clamp part. The set screw wouldn't have to be tight, just snug up to the flat, that would block rotation. There is no easy/obvious way to do this since it is pot metal and has little fins to make it strong rather than being solid. I may later do an metallic epoxy fill to make an area that can be drilled and tapped. A tight fitting keyway and key would be best but probably more work than the tool merits.

- The rig is designed to take a metric Proxxon tool. I made an adapter that is a piece of aluminum tubing and turned it to the right diameter. I then threaded one end to fit into a standard 3/4" threaded nut which also matches the Dremel or B&D RTX tools. I split the nut to reduce it's height and screwed it onto the tube and clamped that in the rig. The RTX just screws into that. The description is longer and more complex that the actual making of the adapter. :D

- I found that even with a brand new solid carbide 1/8" spiral cut mill bit and the B&D RTX cranked to high speed, the transitions between the sap bands seemed to be "jumpy". A non-climb cut has a tendency to want to rip out the wood along the grain when making the initial cuts down the center. If you are slow and don't push it it is fine, but you can't just go at it like you are killing snakes or you will pop a chunk off along the grain. Perhaps a downcut bit might make this a bit easier?? I ended up trying to make an initial cut down the center line, then come back with small climb cuts to just shave away the wood to the template. I followed that by going all the way around with a climb cut as a finish cut.

Overall it did a great job and is way more consistent and a better result that I was getting with my saw. Many thanks to Haans for starting this thread.

Alan D.


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 Post subject: Re: Mini pin router
PostPosted: Sun Nov 07, 2010 7:14 pm 
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Koa
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Alan,

Wow... you put considerable work into this. I hope it works without fail... forever. I do use a down spiral bit in my setup and do not, or, have not noticed any issues with cutting directly on the line the first time either way. Of course I don't go at it like you wrote, "like you are killing snakes"!

This one has his eye on you.
Image

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 Post subject: Re: Mini pin router
PostPosted: Mon Nov 08, 2010 1:56 pm 
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Cocobolo
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Joined: Thu Dec 22, 2005 4:17 am
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Heh, heh, don't want to kill that one, what a cutie! As it turns out running the RTX almost on it's highest setting helped with the feed a lot. I was able then to just follow the pattern but I did still notice that a climb cut (rotation towards the pattern edge you are following) seems to work best and have the least chatter going through the grain bands.

Still and all, a very slick tool and makes the F-hole cuts very clean. I just rounded the edges a bit with some sandpaper and didn't even bother to do anything to the actual edges of the holes. Many thanks for starting this thread and sharing your tips/tricks.

Laters,
Alan D.


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 Post subject: Re: Mini pin router
PostPosted: Mon Nov 08, 2010 2:43 pm 
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Koa
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Alan,
I just remembered... I glue on my reinforcement (backing) gauze before I cut the f-holes. I am sure this is the reason I don't notice any tear out or splitting.
chris

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