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I’ve had a Delta X5 16/32 drum sander for about 20 years. It has served me well, but parts are no longer available. A few weeks ago, someone mentioned the Jet 2244 Oscillating sander here. I looked into it and it seemed interesting. It was on sale last week. I bought one. It is nice—it’s faster and leaves a nice finish without scratch marks even with 80 grit paper. But, there seems to be a .006” dip in the conveyor table leaving the middle of a sanded piece thicker than the edges. The table is stamped not cast and milled steel. Am I wrong to expect better? I’m thinking that half that would be okay, but when I’m working with backs at .095” and sides at .080”, .006” variation is a big deal. Should I be expected to flatten the platen on my own (like we tune a new plane)? My Delta sander had a cast and machined table and was right on. I’ll call customer service next week hoping they’ll trade me a flat table for this one. Or, am I just too picky and I should deal with this myself?

Sorry to hear that Bob. A few years ago I bought an oscillating horizontal edge sander (Griz). Of course you want it to sand edges or anything else flat. The platen is 30x8" and if you ran a straightedge corner to corner the ends were 1/4" off the platen.

They said I could send the machine back at my expense for a refund. Or they would send me a new platen to install myself. They refused to pay someone to come to my shop and make the swap.

I ended up doing it but it took about 10-12 hours including boxing up the old part they insisted I send back.

I kinda expect Jet won't be able to relate to 0.006" as an issue in woodworking.

Did you put a straightedge corner to corner and actually measure the 6 thou? If it is a stamped part and not thick it may be pretty hard to flatten.

Large thin panels tend to flutter around the edges and or just not be perfectly flat and the edges tend to get sanded a little thinner between the rollers anyway, exacerbating a warped table.

Good luck and let us know how you make out.

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Brian R, Wood Mechanic
N8ZED

My Delta has a bit of a dip in the center as well. When I had a guy come over to look at it he basically said that’s what you can expect at that price point.

I really want that same machine myself. Personally the .006 dip wouldn’t bother me. Having the edges of a top and back panel be slightly thinner than the center is not a problem to me. If you do your sides perpendicular to the roller on the last few passes, there’s not going to be a .006 difference over the 5-5.5” of the sides. You can also rotate the side on the final pass without adjusting the height. If the dip really bothers you, you can make a carrier sled. Would love to hear more about this machine once you’ve had some time with it, particularly how well it works for making purflings at .02-.03…

I have read on forums the exact same thing. One guy stiffened his bed with angle iron, based on a discussion with a factory tech.

Does your machine have a spec for flatness? I thought my SuperMax had a finished sanding flatness spec but I could not find it in the UM. I DID just now find this on a "Sell Sheet":

• Flatness Guarantee: Precision-flattened steel conveyor bed reinforced
  with four steel cross sections for no “flex” in conveyor, guaranteeing
  flatness to less than .010″ across the width of the sander.

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Measure Twice,

Karl Borum

I have a cheeper drum sander (grizzly) when sanding back and sides I use a carrier board made of 1/2 baltic plywood that has been ran through the sander going the same way until it cleaned up, arrows on the edge show the feed direction.
Put stick on sand paper on the top side to keep the part being sanded from sliding around,the carrier board is large enough to support the entire piece.
Not sure if this will work on your sander but it seems to help with mine

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Say what you do, Do what you say.

I have an ancient Performax that has the same stamped steel bed. I've done the same thing as Dave does, using a 3/4 Baltic Birch bed with sandpaper on it as a non slip grip. Works great.

Dave

Like Dave and Dave, I use sleds sanded to match the drum but use 3/4 MDF or another flat material. Also the sleds are sized for what I'm sanding, joined or unjoined backs, sides, and also one for fretboards which make a preliminary radius on two passes. I have a Jet 22-44 OSC too, way better than the old Performax 16-32. The sleds can also be tuned for flatness if you're finding a sideways taper in the top/back by flipping it end for end and sending it through a couple of times.

Thank you to all. The sled is a simple and obvious solution I hadn’t thought of. I was stuck on flattening the platen which was going to be a long job given the required disassembly. I was considering putting a graphite surface on the platen like on a belt sander. I routinely true the platen on my belt sander by scraping the graphite. I like the sled. It’s a simpler solution.

A sanded panel was 6 mils thicker in the middle. I was able to detect the dip in the middle of the platen under a straightedge, but the sandpaper conveyor belt made it hard to get a good measurement with a feeler gauge, so I went with the difference in the sanded thickness. I was used to getting a flat top and a flat back (within a couple of mils) with my Delta sander, so the 6 mils bothered me. I didn’t realize that I was that lucky.

I could find no specification for flatness for my new machine. But if the competition is bragging about .010” flatness, I guess I should be satisfied with .006”.

I’d be curious to know what real world results would be for sanding a side as is…

I recently bought this machine second hand, so I have only limited experience with it, so far.
That being said, I recently sanded a set of wengé back and sides on it. I must admit I didn't think it would work out as well as it did. Surface finish was really nice, straight off the 100grit paper I used.
I did many very light passes, with the pieces in different directions, and at different points under the sanding drum. This way, I was able to get the sides pretty consistently to a uniform thickness of 1.8mm (without using a sled). I would say differences in thickness across the sides was below 0.2mm. Considering I always finish my sides with a scraper, this was easily remedied in the finishing steps.

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http://www.vanguyseguitars.com

Interesting - I have a King 16" Closed End Drum Sander, it does the exact same thing, .006" (or more) thicker in the middle than at the sides.
I tried running the plates through on top of a 3/4" flat MDF carrier, but the results are the same.
I have learned to live with it....

I’ll try to remember to post after I do some sides. I expect they will be okay. The dip area is wider than a typical side.

That sounds like the drum is flexing.

Running a side through the middle gave results edge, middle, edge: .074”, .075”, .073”. The differences are within measurement errors. I did more testing with tops. Pretty consistently it was .006” to .007” thicker in the middle than on the edges, dropping sharply within the last two inches on each side of a 16 inch wide top. It seems like there are a couple of lengthwise supports in those locations under the platen. I’m sure the sled will solve the problem.

This sander gives quite a nice finish without apparent scratch marks. I changed the paper from 80 to 100 grit and it got even better. I like this sander.

The sled has solved the problem. Thank you to all.

Have you made purfling with it yet?

No. Probably won’t any time soon. It’s rare that I make my own veneer for laminating purfling. Sorry. I did make a few veneers with my old Delta sander. That worked okay. I didn’t go as thin as the .02” that I could buy.

I have a different challenge in mind for it, but I won’t get there for a few months. I plan to do some experimenting with nomex.