Wood Board Thickness - erratic

[gkas]

Hi Steve,

What brand/model drum sander are you using?

It's a Performax 16-32. I'm not sure if they even make them any more. Jet bought them out a few years ago but all of the parts are interchangeable. The sandpaper rolls are a little pricey. Especially if one tries to use it as a thickness planer.

I recently purchased the Performax Supermax 19-38 Drum Sander. I love the thing. You CAN flatten reasonably short pieces of wood. The bed is flat, so you can run pieces through as long as they don't wobble. If they do wobble a bit, tack them down with hot glue on a carrier board. It takes up to a 4" thickness. One side is now flat, so flip it over and pass the other side.

It certainly does not replace a planer. On the other hand, I have used it to take off a 1/4" off some short pieces. Those are the pieces that won't run through a planer. It will sand down pieces as short as 2-1/4". When you cut off a box top, you can sand down the cut edges. Beautiful result.

Yup, the sandpaper rolls are a little pricey. But, this provides some solutions that were previously a bear to solve. .....did I say I love my drum sander?

[ezurick]

If I get a 6" jointer, will that be able to successfully plane a 12" board by flipping it? Meaning joint one side and turning it around and doing the other side. Will it be level?


If you are getting differences in thickness across the board might be worth checking that the cutting head is sitting parallel to the feed table on your thicknesser, don't trust the factory settings on a lot of these machines at the cheaper end of the market, I have a thicknesser that I believe is the same sort of benchtop machine from a google search, out the box it was off by quite a bit, thought about taking it back but figured that the next one could be just as bad so just spent the time to adjust it myself

I believe the planer cutting head if fine.. I am measuring BEFORE I plane and I am getting erratic dimensions on the same board. As I said above, I decided to try and eliminate some of this by purchasing Lowes premium boards (red oak, yellow pine, poplar) and they also have erratic width issues. Not as bad as the cheap boards, but enough to make me have to mill the top to do precision carving like engrave.

I am also like you... not a whole of resources for used equipment around my area. And I am a bad beginner with CNC.. I am even worse at mechanical repair... lol. For this CNC, I am learning and actually having a little enjoyment sometimes. My wife tells family & friends that she can't believe how much time I spend down there with that machine. I think she thought I'd buy a $1200 machine only to collect dust after a while (like my $900 24" vinyl cutter)... lol.

However, someone posted below that it is possible to use a 6" jointer on a 12" board. That might be promising. $400 would buy me a nice 6" jointer brand new. Do you have box stores over there in Scotland?

[Rcnewcomb]

Here is an overview of a wide belt sander that a guy built from scratch using salvaged parts. The pressure regulators came from beer kegs.

[gkas]

I use my CNC for edge jointing, especially with glue-ups. I only have a folding construction table saw, so it's actually faster than the saw. I pencil mark on the edge, then make small full depth passes on the edge. I don't even draw anything. I just use the pendant to set up the bit, turn on the motor, make a pass, turn off the motor. Rinse and repeat. I pencil the edges on each pass. Line removed=edge straight.

[Wayne Locke]

I started to reply when you first posted but others beat me to the draw. Are your numbers correct? Are you v carving to 0.003"? That's roughly the thickness of a piece of paper. There is no way that you can v carve 3 thousandths of an inch in wood. You couldn't sand it at all if you could do it. As others have pointed out - if you expect wood to be accurate to .001" you are bound to be disappointed. You just can't do it.

Also, you cannot true a 12 wide board on a 6" jointer unless you cut the board in half, joint both halves and then glue them back together.

[jfederer]

As SteveNelson46 said, a planer can be used as a wide jointer. For the last few years I used a DeWalt 735 which I just sold for half retail. The buyer got a lightly used machine in excellent condition. For a warped board, just build a rugged sled and shim the warped board to get the first side flat and true, then run the flat board on its own for a consistent thickness. The DW735 is a really reliable workhorse, has been on the market for years, and is a favourite of woodworkers. It retails for about CAD700 but can be found on sale quite frequently at Home Depot and Lowes. On the other hand, you COULD buy a 12" jointer, but it'll cost you about 4x as much (or more) and jointers are finicky with wide boards. You have to apply enough pressure for a consistent cut, and the wider the board, the stronger and heavier you had better be. How do I know? I sold my DW to get a 16" jointer. My 65 kg makes it hard to flatten a wide board.

All that being said, wood is not metal. There is no way a 0.0003" v-carve is going to show on the wood, no matter how flat. I've been doing quite a bit of fine detail v-carving, and I would say that 0.040" to 0.060" is a good place to start for hardwood. I'm engraving a makers mark on walnut, and 0.060" looks about right. On softwood or MDF, you will lose all fine detail with even that depth of cut.

[ezurick]

Here is an overview of a wide belt sander that a guy built from scratch using salvaged parts. The pressure regulators came from beer kegs.

That is way out of my league... Thanks for the info tho

[ezurick]

I started to reply when you first posted but others beat me to the draw. Are your numbers correct? Are you v carving to 0.003"? That's roughly the thickness of a piece of paper. There is no way that you can v carve 3 thousandths of an inch in wood. You couldn't sand it at all if you could do it. As others have pointed out - if you expect wood to be accurate to .001" you are bound to be disappointed. You just can't do it.

Also, you cannot true a 12 wide board on a 6" jointer unless you cut the board in half, joint both halves and then glue them back together.

Ok, I looked back at my earlier posts and I see I gave wrong measurements and sometimes added a zero. I thought I cleared that up after I posted about the example measurement.

I've had new pine boards from Lowes do this... With my digital caliper I measure and it might be .728. I flip it over and measure and it might be .748. On say a 15" length board... I do the same on the other side and get an erratic difference measure of something like that. A planer won't fix that of course. Secure that board and if I am doing an engraving of .003 depth, a difference of .02 MAKES a difference. Depending where the zero is on that erratic depth, somewhere will be .003 cut and some areas will barely touch the board. The only way to correct this (that I know of) is to mill the top first.

And I see someone deleted their post that stated you "could" level a 12" board on a 6" jointer. Other say no.

[dealguy11]

You can't remove twist from a 12" board on a 6" jointer. You can, however, do it with your planer using a sled and shims, as described above. You need to start with a really flat piece of wood for the sled, like a piece of MDF. Put a cleat on the front end (the end that goes in the planer first), being careful to keep any fasteners out of the way of the blades. Butt the piece you're flattening against the cleat. Insert shims under the board to keep it from rocking, and fasten everything down with hot glue. Plane the top until flat. Remove the board from the sled and flip it to plane the other side. Should now be flat and the two sides should be parallel.

Also, make sure the grain of the wood goes up towards the back of the piece to minimize tearout.

[martin54]

That is way out of my league... Thanks for the info tho

Well you don't have to build anything quite so complex or industrial grade to get a useable drum sander

can't find any finished pictures of mine but I made one from plans I bought a few years ago

[ezurick]

You can't remove twist from a 12" board on a 6" jointer. You can, however, do it with your planer using a sled and shims, as described above. You need to start with a really flat piece of wood for the sled, like a piece of MDF. Put a cleat on the front end (the end that goes in the planer first), being careful to keep any fasteners out of the way of the blades. Butt the piece you're flattening against the cleat. Insert shims under the board to keep it from rocking, and fasten everything down with hot glue. Plane the top until flat. Remove the board from the sled and flip it to plane the other side. Should now be flat and the two sides should be parallel.

Also, make sure the grain of the wood goes up towards the back of the piece to minimize tearout.

Thanks... this might be a challenge but sounds reasonable. I am unfamiliar with the hot glue process, but I guess I can learn. Is this the hot glue type thing that Walmart sells in their crafts areas? It's a hot glue gun? If so, I already have one. I bought one for my wife's crafts, but her or I never used it. Doesn't it err the wood or stain it, say white pine? And I assume you be sparing on the glue?

What do you use for the cleat fastner? Perhaps secure it permanently with gorilla glue? Think that would work? Also, the challenge for me would be getting it shimmed properly and then secured at the proper level. But I think I will try this. Like so many things... sounds and appears practical.. until I try to do it... lol. Thanks again. BTW... I have heard of folks using a flat waste board and shimming the piece on a planer. I just didn't know how to go about doing it.

[ezurick]

That is way out of my league... Thanks for the info tho

Well you don't have to build anything quite so complex or industrial grade to get a useable drum sander

can't find any finished pictures of mine but I made one from plans I bought a few years ago

sander.jpg

That is pretty nice. But still, I think it might be a bit above my 'builders' skill level. I live in the country of NC and there isn't much for resources, like we've stated before. I wouldn't know where to acquire a roller like that. Or even a smaller one. But I'm gonna keep trying on my planer with flat MDF and shims. For quick projects that need precision, I'll just mill the top.

[martin54]

The rollers are class 7 plastic waste pipe, not sure what your equivalant would be but its the thickest wall you can get. Think it was 100mm (4 inch) for the sanding roller & feed table is 50mm(ish) (2 inch) It is all made from stuff that is quite easy to get hold of, Plywood box plywood inserts on waste pipe for rollers. Threaded bar through rollers & off the shelf bearings I cut all the bits on the cnc for accuracy as like you I don't have a decent table saw. it was easy enough to redraw so I could cut on the cnc. Can't remember what the motor came from but I just used pulleys to gear to correct speed.

[Bob Reda]

The one topic no one has asked is are you using construction grade lumber or furniture grade? The moisture content is way different in each

[dealguy11]

Yes, just craft hot glue using a standard craft hot glue gun. The glue shouldn't stain the wood and even if it does, so what, since you're going to plane off the part where the glue was. You can gorilla glue the cleat to the sled if you like. I usually screw it from the back. If you keep the cleat shorter than the thickness of the board being flattened then it shouldn't engage the blades. It's only purpose is to make sure the sled gets pushed through the planer when the planer rollers engage the top of the work piece. Good luck!