Shop-Built Thickness Sander

[Guitarnut]

Well, I'm at it again. Adding more function to my Shopsmith. There are times when a thickness sander is a better choice than a planer. I plan to start building acoustic guitars at some point and there's a real need for gentle dimensioning that a planer just can't do.

If you followed my recent swing arm sander build, you may have seen my plan for a drum sander add-on to the belt sander. It would be too narrow to do the work needed for acoustics.





So, I've been thinking about a stand alone sander that would be powered by the Shopsmith. This is what I've roughed out. Still lots of details to work out but it should be much easier than the belt sander.

It will rest on the way tubes and be powered using the Shopsmith quick connect coupler. Four gears on a chain drive will adjust the height of the table. At the moment, the design is manual feed but I want look at adding a power feed...one of the details I still need to figure out.

It might be a few weeks before I start the build but I'm collecting parts and pieces and continuing the design process.

[DesertGroomer]

I think you are going in the right direction with your last idea. I built something very similar using an old wood lathe as a power source and it works like a charm.
However, my table rising system is much simpler: The table is hinged on the back and has only one height adjustment screw in the middle, at the front. It forms sort of a triangle, so it's very stable.
I added a carrier that slides back and forth over the table (in lieu of the transport belt), for short pieces. For long pieces it's not necessary.
I regret not installing 2 small diameter rollers alongside the sanding drum, at the infeed and outfeed, to hold the material down, because depending on the size of the pieces sometimes I get some snipe.

GOOD LUCK!

Rico

[Guitarnut]

Originally Posted by DesertGroomer

I think you are going in the right direction with your last idea. I built something very similar using an old wood lathe as a power source and it works like a charm.
However, my table rising system is much simpler: The table is hinged on the back and has only one height adjustment screw in the middle, at the front. It forms sort of a triangle, so it's very stable.
I added a carrier that slides back and forth over the table (in lieu of the transport belt), for short pieces. For long pieces it's not necessary.
I regret not installing 2 small diameter rollers alongside the sanding drum, at the infeed and outfeed, to hold the material down, because depending on the size of the pieces sometimes I get some snipe.

GOOD LUCK!

Rico

Thanks Rico! Some good input there.

[Guitarnut]

Well, it's rainy and cold this morning so I can't put clear coats on my Challenge build as planned. So, I did bit of design work on the sander.

I changed the shape of the housing to allow for mounting bearings. I'll use the same bearings that I used on my belt sander project.



I also worked out how the lead screws would be anchored. My plan is to pin the gears to them and have them thread at the bottom into a threaded block or nut. The tops will be pinned into lighter flange bearings that hold them in place but allow them to spin.



I salo started on the design of the height adjuster. At this point, it looks like just adding a fifth gear and lead screw will do the trick. The handle will be under the front of the sander. I'm thinking if I back time the lift gear just a hair of the others, it will move the chain, lift the 4 corners on their respective threads and never exert upward pressure on the chain. I'll have to test it to see if it actually works that way.



This fifth gear will also act as a chain tensioner. I'll have to get the other 4 in place and time them before I set it's location.

[Warnz]

He's off again

I'll be watching

[guitarbuilder]

Just my 2 cents having built one with a piano hinge. The hinged design is proven and probably the results would be just as good as what you are proposing unless your frame and drum materials are so rigid that they'd be like cast iron.

[Maricopa]

You really need a couple pinch rollers. One on either side of the drum.

[Guitarnut]

Originally Posted by guitarbuilder

Just my 2 cents having built one with a piano hinge. The hinged design is proven and probably the results would be just as good as what you are proposing unless your frame and drum materials are so rigid that they'd be like cast iron.

Now if we all did things the way everyone else does, who would build the guitars out of popsicle sticks or concrete? Hmmm?

[guitarbuilder]

You got me....:-)

[Guitarnut]

Originally Posted by Maricopa

You really need a couple pinch rollers. One on either side of the drum.

Yeah, I haven't thought that far ahead but you're probably right. I'm thinking just a spring in a slot to bear down on the axle and washers either side to keep them centered.

[Guitarnut]

I made some good progress today. I had the supplies on hand to make the roller so that's where I started.



I decided to make the drum 20" wide. That was a little too wide to just let the PVC support itself so I made a few extra hubs to go inside the drum.

I cut all of the discs out of 1/4" PVC sheet.



Then glued them up using a 1/4" bolt in the vise to keep them all centered. Using standard PVC cement, I coated both surfaces, gave a 10 count and then pressed them together. When I had each stack completed, I added a nut and washers to clamp them for a few minutes.







After they set up for 20 mins, I started lathing them to true them up and take them down to size to fit inside the PVC pipe.





last thing I did was draw a line around the center. This will help me sight them through the screw holes when screwing them to the drum.





After drilling them out to 1/2" bores, I drilled 1/4" holes in the axle and bolted the hubs into position. By countersinking the heads, I had enough thread to put jamb nuts on each one. I also alternated them 2 heads up, an 2 heads down to keep the assembly in balance when it spins.





Then, I tapped the axle assembly into the PVC pipe...like a glove.

[Guitarnut]

Originally Posted by Warnz

He's off again

I'll be watching

[mgdesigns]

I can make you a sweet deal for a 1955 Greenie headstock to power it. PM me, and we can see what we can work out.

[Crafty Fox]

Since I lack your ingenuity/tenacity/imagination I bought a wide drum sander a few months ago. Mine is single sided, 400mm wide which is wide enough for any guitar build I'll ever do, but good for furniture work giving me the ability to sand up to 800mm wide (on 2 passes).
I was wondering if you could tweak yours to be open on one side? I have no idea how, that's why I bought one.

[raito]

Wouldn't you want the larger wheel on the table and the smaller on the drum? That way, the drum spins faster than the table moves.

[Guitarnut]

Originally Posted by mgdesigns

I can make you a sweet deal for a 1955 Greenie headstock to power it. PM me, and we can see what we can work out.

I know it would be a sweet deal and I appreciate that but I'm not in the market for another SS. I don't have the room right now. Thanks for the offer Mark.

[Guitarnut]

Originally Posted by Crafty Fox

Since I lack your ingenuity/tenacity/imagination I bought a wide drum sander a few months ago. Mine is single sided, 400mm wide which is wide enough for any guitar build I'll ever do, but good for furniture work giving me the ability to sand up to 800mm wide (on 2 passes).
I was wondering if you could tweak yours to be open on one side? I have no idea how, that's why I bought one.

I think the frame would have to be made of steel to accomplish that. My meager means have me strapped to wood only at this point. And, the width I'm building will handle all I will throw at it.

[Guitarnut]

Originally Posted by raito

Wouldn't you want the larger wheel on the table and the smaller on the drum? That way, the drum spins faster than the table moves.

If you're referring to this design, it reverses the setup of a standard drum sander. If you look closely, the upper drum is the feed roller and the belt below is the abrasive surface...it was an early thought as an add-on for the belt sander I previously built. So the pulley relationship would be correct.

However, it's not the design I'm moving forward with.

[Guitarnut]

I added pinch rollers to the design. I'm not sure what I'll use to make them. I'm thinking maybe MDF discs coated in that rubber tool dip coating? Might work.

I thought I posted these earlier but I guess I didn't hit the right button...hope I didn't post them in someone else's thread.

[Warnz]

Hi Mark

Check out "take up bearing units" for the pinch rollers, they have guides machined into the sides for the vertical movement and will also house the pressure springs. As for the rollers themselves you could use some plain round stock (sized for the bearings) and stick a bicycle inner tube to them.

How are you going to drive the workpeice through the sander??