The Shop > Wood & Stuff
Banjo Build
RussellT:
Simon
I don't know how thick it has to end up but there seems to be a lot of material to remove. Could you use a jig saw to take some of the wood out - if you can't find a long enough blade you could make an angled cut to remove some material.
The area glueing it to the face plate will become smaller as it gets thinner. How about making some clamps around the edge of the faceplate, or even screwing the banjo on if the screw holes could be hidden later.
I'm following with interest. :thumbup:
Russell
S. Heslop:
--- Quote from: Will_D on May 07, 2015, 06:18:51 AM ---Simon,
I really admire your ability to take some pieces of plywood and build machine tools that work.
And boy do you test them to the limit!
Keep safe and keep up the good work
--- End quote ---
Continuing the theme, the conveyor motor on the thickness sander stopped working. Got a surprise looking at the electronics, but it seems that the mosfet got hot enough to melt the solder on the leads attached to it and they fell off. Surprised it could even still work at those temperatures. I remembered I forgot to put a diode over the motor and I wonder if it's just inductive currents from the motor causing that, but it could be what bluechip suggested in that thread with the power supply being too crappy to keep a stable voltage to the rest of the circuit.
--- Quote from: RussellT on May 07, 2015, 08:24:25 AM ---Simon
I don't know how thick it has to end up but there seems to be a lot of material to remove. Could you use a jig saw to take some of the wood out - if you can't find a long enough blade you could make an angled cut to remove some material.
The area glueing it to the face plate will become smaller as it gets thinner. How about making some clamps around the edge of the faceplate, or even screwing the banjo on if the screw holes could be hidden later.
I'm following with interest. :thumbup:
Russell
--- End quote ---
My experience with jigsaws and deep cuts in the past is that the blade tends to wander. I did think about ways to rough out the material (was considering trying it with a router, as dangerous as that may be. But I couldn't think of any ways that wouldn't end up being more work than just turning it off.
Anyways I got the board glued back on and drying now. I was shy with the glue since I wanted it to be easy to separate later, but it was perhaps too easy to separate...
Still trying to think of a good tool geometry. Having a back rake seems like a bad idea since that's what I had, and a side rake might work better but i'm worried that with all the backlash (theres alot!) it'll risk pulling the slide forwards and digging the tool in. I could try a shallow rake (or no rake) but with wood that'd probably leave an awful cut and risk pulling chunks out anyways.
mattinker:
--- Quote from: Will_D on May 07, 2015, 06:18:51 AM ---Simon,
I really admire your ability to take some pieces of plywood and build machine tools that work.
And boy do you test them to the limit!
Keep safe and keep up the good work
--- End quote ---
Maybe Simon forgot to reply, Matias Wandell http://www.sentex.net/~mwandel/ has been an important influence, very interesting aproach to machines!
regards, Matthew
Lew_Merrick_PE:
Simon,
You are now finding out why I use the circular lamination approach to banjo shells. The outer guide is the female piece cut-off from the tool blank first using a bandsaw (OD then ID). By making the tool blank in "halves," the ID of the outer guide may be "opened" to access a drilled hole from which the ID may be bandsaw cut (and finished on a spindle sander). The inner core is a male piece that is easily cut with a bandsaw and finished on a disc sander.
A tire from a 6 inch hand-truck tire is the "clamp." I carefully trim and place the outer (really nice wood) lamination to the ID of the outer guide, trim & fit the next layer in to that, remove the next layer, slather up the ID of the (first) layer, re-insert the next layer, insert the inner core (with inner tube), and inflate the inner tube as the clamp. Repeat as required until your desired thickness is reached.
Another advantage of this approach is that only the inner and outer laminates need to be "matched" and "pretty." The "filler layers" can be whatever wood is structurally sufficient and inexpensive. A fascia of "pretty wood" covers up the "filler layers" and, itself, is hidden by an appropriate edge binding.
S. Heslop:
--- Quote from: Lew_Merrick_PE on May 07, 2015, 11:54:28 AM --- The outer guide is the female piece cut-off from the tool blank first using a bandsaw (OD then ID). By making the tool blank in "halves," the ID of the outer guide may be "opened" to access a drilled hole from which the ID may be bandsaw cut (and finished on a spindle sander). The inner core is a male piece that is easily cut with a bandsaw and finished on a disc sander.
--- End quote ---
I don't fully understand what you mean. But either you've given me an idea or this is what you're saying; but I wonder if I could just make a plywood template for a router bit's bearing to follow, attached to the rough rim. Of course such a deep cut would be fairly dangerous (even if router bits of that length exist), especially with my crappy wooden router lift with questionable rigidity... Perhaps I could've routed each layer separate before glueing them together.
One thing that concerned me with laminate rims is the possibility of it warping. Since (as far as I know) there's no huge shaping after it's been glued up, and you've got a fairly damp thing soaked with glue, won't there be a fair bit of warpage as it dries? I assume that mustn't be that big of a problem since plenty of banjos are made that way, but it's still something I didn't want to risk having to tackle.
Anyways I ground up a tool bit without thinking too hard. I think I just ended up automatically making a bog standard turning tool with heavy rakes and reliefs.
I think trying to use that would be a bad idea since it's got more than a few ways it'd want to dig in.
So I figured that if I ground it again but with no (or very little) side relief, then that would prevent the tool from digging in too deep.
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