drum sander baffling me. .


Brendon_t

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I am helping my neighbor build a huge (35"x19.5") end grain chopping block for his boat. The blank was wider than my planer could handle so I used the drum sander. Flipping end for end each pass. After cross cutting and turNing on end, I fould the ends were thinner than the center. I assumed this was because the drum was not parallel to the bed

Yesterday I took a piece of 16"wide ply and ran it through the same way over and over until it didn't sound like much contact was being made at all.

I pulled it out, measured each side and their only .006" out. .

I'm now wondering if it's possible I was trying to take too much off and not letting it fully flatten the board out. My thought being that the end may have been moving up slightly with the thick loaf under it and I didn't let the sander fully flatten it. .

Any ideas? Does my train of thought work? Is there a better way to check flatness?

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My first guess would be that you were possibly taking too much off, and causing the drum to flex up on the outside edge, which would be the center of the cutting board. But that's just my guess.

 

This is coming from a guy who still can't find a gear for a delta drum sander that I broke 2 years later, from trying to take too much off haha.

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There is a learning curve w drum sanders. Run a board through with the drum turned off, feed belt on medium. You should be able to stop the drum by hand. This is where you start. Especially on end grain never turn the handle more than 1/16 th to 1/8th of a turn for any pass.

What grit were you using and what wood were you sanding?

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I was using 60 grit paper, on maple, walnut, And cherry blank, plus turning the handle 1/8- 1/6 every two passes.

I think that must be the problem. .lifting of the end.

When drum sanding, Should it sound like no wood is coming off any more before lowering it?

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wdwerker is spot on. When I first got mine I had a long learning curve. Everybody reminded me that it wasn't a planner and light passes. I do  the 1/16 turn of the handle now and even less sometimes. Less is more with these things. Can take a little time but worth the trouble 

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.006 is to far out for 60g. The line between 60 and 80 grit the spin the drum by hand rule of thumb goes out the window. You can't spin the drum by hand with 60 grit set to the proper height. The line between 60 and 80 is surface planing vs sanding. .006 is the difference of a full pass. If you were sanding a 6" wide board you would not even notice it but sanding the full width of the sander your going to make wedges.

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.006 is to far out for 60g. The line between 60 and 80 grit the spin the drum by hand rule of thumb goes out the window. You can't spin the drum by hand with 60 grit set to the proper height. The line between 60 and 80 is surface planing vs sanding. .006 is the difference of a full pass. If you were sanding a 6" wide board you would not even notice it but sanding the full width of the sander your going to make wedges.

Pb I've read this the times through and really am not grasping what you are saying. .

The .006" difference is across the entire drum.

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Pb I've read this the times through and really am not grasping what you are saying. .

The .006" difference is across the entire drum.

 

.006 is a full pass with 60g. If your drum is low on one end .006 its going to cut wedges if the workpiece is the width of your drum. If you flip it around and go the other way the wedge will just change direction so now both edges are low and the center will be high. 

If you set your height right for 60g  one side should be cutting and the other side not if the workpiece is the width of your drum.

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You can't just say " this much deviation is acceptable" across the board it depends on the length of your head. You have to look at how many cuts it take the drum to catch up with the deviation. So you have to measure that manually.

 

Take a look at this pic I drew it exaggerated but this is how it works.

 

post-5350-0-65567500-1425584530_thumb.jp

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With that machine, I would make passes so light you can hardly tell it's sanding.  Not to be a jerk by stating the obvious, but we all know how well Ryobi machines are built...I'd say there's a good chance the head is deflecting against even the most insignificant pressure.  Cantilevered heads require better-than-average engineering to perform well...even Performax machines have issues to this day because Jet refuses to fix the problems.

 

Get it dialed in by running a long skinny strip of wood through on each side of the belt and comparing with calipers.  Then run your full-width board.  If it's still coming out uneven, you can probably assume it's deflection.  At least that's what I would assume.  Then I'd get out my credit card and call Supermax. :)

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Ha ha, What ever do you mean eric? I thought ryobi was top of the line? ?

Seriously though, I was looking for a ds and wouldn't commit top $2k for a tool I hadn't used much and want sure I would use often in my work flow. I picked up the machine for sub $200 with about $150 of new paper.

I have found that I love haVing the machine and it fits everywhere within my workflow. I will definitely drop coin on the next one but would like to milk this one as long as I can.

I believe my core problems stemmed f from just trying to take too heavy passes. I will remedy that on my next use.

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Even the super max climbs the stock when using 60g. If your open end is the low side your definitely flexing the machine. Using strips isn't going to tell you what is happening they won't provide same load as a full width end grain block. Change paper to 100 and take the lightest possible passes.

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Don - how would you go about calibrating a cantilevered-head DS then? I've tried full width boards before but I figured if they weren't dead flat they could be skewing the measurements. Admittedly I've never known the "right" way to do this. I've just used the strips on each side method and it seems to work.

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Don - how would you go about calibrating a cantilevered-head DS then? I've tried full width boards before but I figured if they weren't dead flat they could be skewing the measurements. Admittedly I've never known the "right" way to do this. I've just used the strips on each side method and it seems to work.

 

I used my lee valley steel straightedge and some feeler gauges.  It was a bit tough getting the feeler gauges in on the "inboard" side of the head for anyone with hands bigger than a child, but it worked.

 

I took the paper off, laid the straightedge (on its wide side) across the feed, lowered the head until I could get the .001 feeler gauge through the gap but couldn't get the .002 gauge through.  Then I put the straight edge on the outboard side and it was a bit off (was able to get the .002 gauge through.  So I adjusted the allen screw a tiny bit and re-did the test.  Only took a couple iterations of that til I got it dead on.  

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Don - how would you go about calibrating a cantilevered-head DS then? I've tried full width boards before but I figured if they weren't dead flat they could be skewing the measurements. Admittedly I've never known the "right" way to do this. I've just used the strips on each side method and it seems to work.

 

You can set the thing dead nuts perfect. BUT you can't account for load so all you can really do is keep load as low as possible by using reasonable papers and very light cuts. End grain adds to load as does a coarse grit. If you adjust the machine by sanding something like strips your accounting for a light load and just setting the machine up for that load. Change the load and the machine is going to be off.

The problem with adjusting to a load you actually setting the machine up knowing its going to flex and trying to make up for that flex. So in this case with the end grain full width board if you set it up for the actual load you may end up breaking the machine. The machine should be set up not running with no paper on the drum. If your sanding wedges then you have surpassed the machines abilities.

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