Author Topic: Banjo Build  (Read 64350 times)

Offline S. Heslop

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Re: Banjo Build
« Reply #25 on: April 07, 2015, 04:46:08 PM »


Got it back together for now. It was still acting funny but then I realised what the problem was; the crank arm was hitting the horizontal beam at the top of its travel. Helps show how strong those windscreen wiper motors are since it was flexing the whole plywood block that the motor is mounted to instead of stalling it. All that'll require is some adjusting of the yoke to fix it.

There's alot of little things here and there I could do to improve the thing too. I thought up a slightly better idea for the yoke part that i'm tempted to try, but I could get caught up in all this stuff if I let myself. If nothing else I might just update the cad model of the machine.

Looking at the video I took it looks like the thing I was trying to fix in the first place isn't aligned, it's now about as far out in the other direction. With the billions of shims I hope that trying to shift the thing parallel doesn't make the slide jam up. But hopefully it should be easier to do.

Also since this thing was about 99% fiddling I didn't record much of it. And I've neglected to take any clips of putting the shims in.

Offline sparky961

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Re: Banjo Build
« Reply #26 on: April 07, 2015, 07:04:28 PM »
I have managed to set oily rags on fire before while welding though!

A few months back I started a new job.  Within the first month on two separate occasions I set a rag on fire while welding.  Fortunately it was more funny than scary, but unnoticed in a home shop it could have been devastating.

Offline S. Heslop

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Re: Banjo Build
« Reply #27 on: April 08, 2015, 12:57:46 PM »
Got the thing reassembled. Also put the sandpaper on with a thin layer of 5 minute epoxy. It's brittle stuff and the idea is that it should hopefully be quite strong in shear as it sands, but should peel off easily. I'll be replacing the paper when I finish sanding the drum, so I can use some finer stuff to get a smoother finish. So i'll find out if this idea works then.



Not sure if I'll call this whole thing a success though. All I really did was broke everything and fumbled about for a week trying to get it back together. It's still out of alignment and I could try fixing that but... I don't want to end up stuck with another weeks worth of this bullshit.

I suppose I'll get this pot round first and then maybe fuss with the alignment.

At this point though this whole project has taken alot longer than expected (as usual) and i've got some essential stuff I need to get around to. So I might shelve it again after getting the pot round.

Offline Brass_Machine

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Re: Banjo Build
« Reply #28 on: April 08, 2015, 01:55:00 PM »
...
Not sure if I'll call this whole thing a success though. All I really did was broke everything and fumbled about for a week trying to get it back together.
...

That's a line right out of my book! You are not alone...
Science is fun.

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Offline S. Heslop

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Re: Banjo Build
« Reply #29 on: April 11, 2015, 03:58:44 PM »
Where abouts is a good place to buy high speed steel tool blanks? I've checked the usual places (arc euro and rdg) but they don't offer it in larger diameters. Cromwell tools does, but at 20 or w/e for the size i'm after that's quite pricey. Especially since I need a few

I'm trying to make some better wood lathe tools since the price of the tools themselves is incredible, and the profiles don't seem to be anything I couldn't grind and make handles for myself.



Regular chisels don't give alot of leverage and i've had the tool dig in a couple of times. Plus they're going blunt very fast. The outside is fairly smooth already but it'd be a stupid idea to try do the inside interrupted cut with the same chisel.

Also I need to figure out better speed control for that drill. It has speed control but it's fussy, and won't stay at a steady speed. Might try a dimmer switch, but i'll have to check if they can handle the load.

Offline S. Heslop

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Re: Banjo Build
« Reply #30 on: April 11, 2015, 04:29:35 PM »
Actually, forget that. Thinking about it I should really just shelve this project now so it doesn't distract me. I'm not a great multi-tasker.

If I was doing it properly, seriously trying to make a banjo, i'd probably be best off making some sort of lathe from welded steel and buy one of those x-y tables they sell for drill presses. But i've mostly been playing around with goofy ideas that haven't really worked out that well.

I've mentioned in the past about setting up businesses, but with those I was mostly playing around with the idea too. But since my brother got involved i've started taking it more seriously. We've been looking at renting units the last week and we're considering taking out a loan to pay for tools and vehicles. Fleshing out the business plan and all that.

So RIP the banjo, for now.

Offline vtsteam

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Re: Banjo Build
« Reply #31 on: April 12, 2015, 09:25:07 PM »
Leaf springs?
I love it when a Plan B comes together!
Steve
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Offline Will_D

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Re: Banjo Build
« Reply #32 on: April 19, 2015, 06:46:00 AM »
What about 12" or longer files? Either big flat ones or big half round ones. They don't need to be new as its not the teeth you wants its a sharp end. So any old files from the 'bay or the boot would do.

Great quality steel and you could always reforge the ends to make V's and gouges. If you can't forge yourself find a blacksmith!
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Offline S. Heslop

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Re: Banjo Build
« Reply #33 on: April 19, 2015, 08:59:03 AM »
What about 12" or longer files? Either big flat ones or big half round ones. They don't need to be new as its not the teeth you wants its a sharp end. So any old files from the 'bay or the boot would do.

Great quality steel and you could always reforge the ends to make V's and gouges. If you can't forge yourself find a blacksmith!

That's a good idea. I might give it a try.

Offline awemawson

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Re: Banjo Build
« Reply #34 on: April 19, 2015, 09:02:51 AM »
Beware that many modern files are only case hardened - not true of older ones
Andrew Mawson
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Offline vtsteam

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Re: Banjo Build
« Reply #35 on: April 19, 2015, 09:39:30 AM »
I was wondering myself about using the steel in wde brick chisels for home forged tools, since they can be sharpened and case hardening would't work for that. They are usually much more substanial than wood chisels and there's a nice wide slab of metal there. Also big cold chsels found at tag sales sometimes.

I have had good luck forging, hardening, and tempering older leaf springs from junkyards. I don't know about whether newer ones are case hardened. Some are fberglass. :(

For anyone who wants to make their own woodworking and stone working hand tools, a must read is Andrew Weygers two blacksmithing books.
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Offline awemawson

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Re: Banjo Build
« Reply #36 on: April 19, 2015, 10:30:39 AM »
If you are prepared to forge it, rebar is usually hardenable, certainly ok for masonry chisels
Andrew Mawson
East Sussex

Offline S. Heslop

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Re: Banjo Build
« Reply #37 on: April 19, 2015, 02:04:59 PM »
Beware that many modern files are only case hardened - not true of older ones

I got some old one here, Made in Sunderland. They were throwing a whole bunch of worn files out at Tanfield Railway and I asked if I could have any sharp-enough ones. Wish I knew at the time that the steel itself was worth keeping, since there were alot of totally blunt files I left behind.

Offline S. Heslop

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Re: Banjo Build
« Reply #38 on: April 30, 2015, 04:04:21 PM »
I spent a few days reading up on wood lathe chisels and didn't really find much information on how to handle heavy internal interrupted cuts. Plus with the whole arrangement not being too rigid to begin with it seemed kinda dodgy.

So I thought i'd try something different.


It's a wooden arrangement built similar to a metal lathe cross-slide. Alot of the details in this cad are missing since i'm probably going to figure that stuff out in person.


Parts rough cut and arranged.


Used wood glue to attach the paper templates (I was going to mark it out properly but somehow all 3 of my tape measures have gone missing), and it was tough to get off with a chisel. So I tried just sanding it.


And... oh... looking at this photo, i've glued these parts on upside down. Hope that glue is still soft so I can separate them.

Offline S. Heslop

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Re: Banjo Build
« Reply #39 on: April 30, 2015, 04:17:10 PM »
Could just barely separate them. I'll let the residual glue dry and send them through the drum sander tomorrow. I'm getting alot of use out of that machine, much more useful than the spindle sander.

Also I think I jumped the gun on declaring this project dead. Turns out trying to set a business up involves alot of waiting.

Offline efrench

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Re: Banjo Build
« Reply #40 on: May 01, 2015, 04:43:41 AM »
Old planer blades are a good source of high carbon or high speed steel for making scraper type tools. Car shock absorber rods are usually HSS and can be ground into gouges.  Files are a bit iffy as they are prone to cracking.  Be sure to wear adequate face protection when turning.   Scraper tools should be ground with an included angle between 60 and 80 degrees. Use 60 degrees for softer wood and up to 80 for hard woods (hardness not type).

Putting longer handles on the tools will make them easier to control.  My main roughing gouge has a 36" handle.

Offline S. Heslop

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Re: Banjo Build
« Reply #41 on: May 01, 2015, 03:01:58 PM »


I think i've built something very silly.

Still thinking about how i'm going to do the toolpost. Adjusting the cut with the slots in the base were my original idea but i'd have to get it all aligned between each cut. Just advancing the tool in the toolpost would probably work alot better. Facing it with a bit of steel would probably also help, since I can see the tool wanting to squash the wood beneath it from the force of the cut.

Still no idea if this'll even work though, might not be rigid enough to handle the cutting forces (even if it's just cutting wood).

Offline RobWilson

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Re: Banjo Build
« Reply #42 on: May 01, 2015, 03:19:08 PM »
Car shock absorber rods are usually HSS . 

You sure about that ?   :scratch:

Rob

Offline efrench

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Re: Banjo Build
« Reply #43 on: May 01, 2015, 10:09:47 PM »
Car shock absorber rods are usually HSS . 

You sure about that ?   :scratch:

Rob

Yes.  It's easy to tell. HSS will create orange sparks when ground. High carbon steel sparks will be yellow.

Offline efrench

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Re: Banjo Build
« Reply #44 on: May 01, 2015, 10:20:55 PM »


I think i've built something very silly.

Still thinking about how i'm going to do the toolpost. Adjusting the cut with the slots in the base were my original idea but i'd have to get it all aligned between each cut. Just advancing the tool in the toolpost would probably work alot better. Facing it with a bit of steel would probably also help, since I can see the tool wanting to squash the wood beneath it from the force of the cut.

Still no idea if this'll even work though, might not be rigid enough to handle the cutting forces (even if it's just cutting wood).

I think you would be better off with turning the original toolpost 90 degrees and make a beefier tool that can handle a two or three inch overhang.  One easy to make boring tool for wood is to drill a hole in the end of a 3/4" mild steel rod and insert either a round or square HSS tool bit in it.  Secure it with a set screw.  The hole can be anywhere from 90 degrees to the axis to on the axis.  Broken endmills work well for this.

Offline S. Heslop

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Re: Banjo Build
« Reply #45 on: May 01, 2015, 10:39:52 PM »
I think you would be better off with turning the original toolpost 90 degrees and make a beefier tool that can handle a two or three inch overhang.  One easy to make boring tool for wood is to drill a hole in the end of a 3/4" mild steel rod and insert either a round or square HSS tool bit in it.  Secure it with a set screw.  The hole can be anywhere from 90 degrees to the axis to on the axis.  Broken endmills work well for this.

That's not a bad idea. I'm not so worried about the tool itself having too much overhang though, and more concerned that the extra leverage will cause trouble with the fairly flimsy wooden arrangement.

Offline chipenter

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Re: Banjo Build
« Reply #46 on: May 02, 2015, 01:32:56 AM »
I would use TC inserts just bolted onto a bar with a lever arangement for feed , there are wood turning chisels that take inserts available and they last for ages , 
Jeff

Offline RobWilson

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Re: Banjo Build
« Reply #47 on: May 02, 2015, 04:04:14 AM »
Car shock absorber rods are usually HSS . 

You sure about that ?   :scratch:

Rob


Yes.  It's easy to tell. HSS will create orange sparks when ground. High carbon steel sparks will be yellow.


Interesting , I will look into that , just cant see why they would use a tool steel in car shocker rods .


Rob

Offline DavidA

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Re: Banjo Build
« Reply #48 on: May 02, 2015, 07:54:31 AM »
Efrench,

It's not that simple.

There are lots of steels that will produce sparks of this colour.

I spent the last seven years of my working life producing samples for spectrograph (and chemical) analysis. There was a lot of grinding involved in this.

We  had a few shock absorber shafts to check,  as I recall,  non of them were made from HSS. Just heat treated high quality steels.

I suppose one could test this by getting an old shock absorber shaft and trying to make some lathe tools from it. See how the edge holds up.

Dave.

Offline vtsteam

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Re: Banjo Build
« Reply #49 on: May 02, 2015, 12:46:28 PM »
Now there's a practical suggestion.  :thumbup:
I love it when a Plan B comes together!
Steve
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