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We started to get into a discussion of the Performax 10-20 in the thread on thicknessing with a Safe-T-Planer. I raised some more questions, then decided it really ought to be its own topic, so I'm going to cut and paste the bulk of my last post here (see that thread for the context of this post). I don't intend this to be a conversation between just Hesh and myself - comments/input/help from any 10-20 users would be most welcome:


Interesting, Hesh. Though I am generally happy with the capabilities of the 10-20, this double-pass ridge is an issue I do have some trouble with. I've tried adjusting the drum so that the outboard end is a bit higher, but I've found that I still get the ridge unless I make the outboard end so much higher that the unevenness in thickness across the width of the board is unacceptable. I also find that the ridge is not so easy to sand out with an ROS. The way the ROS rides up on the ridge, it will sand a slight concave area on the downhill side of the ridge. I have better luck with a sanding block, but it can still be somewhat frustrating. I am able to minimize the ridge by ending my drum sanding with many passes through the 10-20 leaving the depth adjustment where it is (I always end with at least a few passes this way, anyway), but even this doesn't completely eliminate the ridge and is a bit time consuming and frustrating. This is the main reason why I sometimes wish I had a wider drum sander (a wide belt sander isn't even a possibility for me at this point).

It's fascinating that you have seen the ridge problem disappear over time. I wonder what change has happened... I can think of three possibilities: 1) that you've gotten better at wrapping the abrasive very tightly around the drum; I've found that, if there's a little slack in the abrasive wrapping at the ends where it goes into the slot on the drum (an easy situation to inadvertently create), the ridge is worse, 2) that the drum adjustment has slipped slightly into a new position, with the outboard end a bit higher, and 3) that something in your habitual sanding procedure has changed; maybe you tend to take a lot lighter passes, especially for the last several times through. Still, based on my experience, I'm puzzled as to how the ridge problem could have disappeared entirely. Any thoughts on this?

Another issue I have with my 10-20 is uneven thicknessing down the LENGTH of a workpiece. This is really only an issue with thicker boards (e.g. neck blanks for scarf-jointed necks, or boards I'm resurfacing during resawing). I find I end up with a slightly concave board, thicker at the ends, thinner in the middle. I attribute this to flex in the table: according to my theory, as the board enters, it's leading end is pushed down into the table by the drum; the table flexes in the middle, allowing the board to be pushed down, and therefore less material is removed by the drum until the leading end of the board reaches the far side of the table. There, the board is bridging both the front and back edges of the table, where the table is much more rigid, and the board's own rigidity keeps it up against the drum, so the drum is removing more material (this is why, I figure, this issue is minimal when thicknessing thin plates, because the wood itself flexes so easily that it is still pushed down in the middle [along with the flexing table] by the drum). At any rate, I can get upwards of .015" difference between the thickness at the ends and the thickness in the middle. This, too, can be lessened somewhat by taking lighter passes, but not, in my experience so far, fully eliminated. The result can be on the borderline of what I consider to be within tolerances. In my casual examination of the machine, the design/construction of the table is an obvious weak point. I keep thinking about modifying it somehow - welding a couple of beams into its underside or something - but haven't looked closely at options for accomplishing that. Any thoughts on this issue?

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

When mine arrived the belt was well centered and the drum was leveled pretty good. but after a month or so I started noticing that the inboard side was progressively getting thinner. I followed the level instructions except I used a 10" long machiest gauge block instead of a steel straight edge ruler as the manual states and it has be fine every since.

I too run at 30 on the feed rate slower some times and take small bites. I went with the 10-20 for economic and shop space reasons. I was worried I wold regret it but have to say it has worked well for me.

Thanks, Hesh, for your thoughtful response. Thanks for your comments, too, Michael.

Interesting that you guys both use a slow feed rate. I usually go full speed on the feed, though I also never turn the crank more than 1/8 turn per pass. I generally turn it about 1/12 of a turn per pass, actually.

Hesh, when you said:

"I really take my time when sanding doing both sides at the same settings and never lowering the drum more than 1/8th turn of the crank at a single time. After I make a pass on both sides on the same setting the last side that I sanded is now the first side that I will sand when I lower the drum in the next pass."

... were you talking about making double passes of a wide board, such as a glued-up top or back? Is that what you meant by "both sides" (rotating the board so that the side that was left is now right)? Or were you talking about flipping the board over so that the side that was up is now down?


As an aside: I specifically do not flip the wood over (top-for-bottom) with each pass when I'm sanding tops, sides, and backs. Before I even begin sanding, I've chosen my "show" faces, according to the best bookmatch, and made little marks on the edges of the boards so I don't get mixed up on which side is which. I sand the show faces just enough to get them flat, remove any saw marks, etc. While doing that, I am generally flipping the wood over and over, sanding both sides. But as soon as the show face is smooth and flat, I stop sanding that side and do all the rest of the thicknessing by removing material from the other side. This preserves the best possible bookmatch.

I suppose everybody knows to do that and I am just stating the obvious.

Anyway, I will experiment with a slow feed rate and see if this does anything to improve the results I'm getting. I will also pay more attention to my drum wrapping and see if there's any fine-tuning of technique that needs to happen with that.

Interesting observation about the off-to-the-right feed belt possibly being responsible, at least in part, for the lack of a sanding ridge on double wide passes, Hesh. BTW, I have always found it impossible to keep the feed belt centered for very long. Maybe I'll try getting it over to the right and see if that does anything to the ridge.

One more thing, Hesh, regarding the uneven thickness issue I was talking about. I guess I didn't make myself clear. It's not that I'm getting an uneven thickness in the center of the drum. It's uneven thicknessing of a board in the *lengthwise* dimension (along the length of the board itself, not the length of the drum): thicker at the leading and trailing ends of the board, thinner in the middle area. And again, this is only an issue when thicknessing relatively thick boards. I hope that cleared up the confusion... if you reread that part of my post above, with this clarification, maybe you'll have some other thoughts about that.

Thanks again. Other comments and commenters still welcome.     

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Hey guys, another proud 10-20 owner here. I have noticed issues with the feed belt also. My belt rides near the center most of the time, but it is noticeably tighter on the left side. The slack on the right side can make it appear to work as though the drum is not parallel. i.e when I level the drum with a rule, I still get a more aggresive cut on the right side but mostly the last 2 inches or so. I like this, actually, and use it to feather the edges of tops and backs. I use the sander angled more than I do flat. I also noticed when I was setting it up that on a level surface, the bit under the outer edge did not touch the table. I am talking about the bottom of the machine, the part that rests on the table. I built mine into my bench and built small in and out and side feed tables around it. I had to shim under the outer edge to secure it and to level the table with the feed tables I built. Without those shims, I was getting some play with more aggresive cuts. Speaking of cuts, I too use the fastest rate. I always thought that it reduced build up on the paper. I'll have to give a slower feed a try. I heard of someone running a piece of plexiglass through to clean the belt. Has anyone ever tried this? It seems like it would make an awful mess but if it works...   I really love the machine, I can take sheets down to .025 for purflings without a dummy board and it fits in my small shop with no problems.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

Todd,
   Check your extention tables(not the conveyor table). If the infeed and or outfeed are raised a little high you will raise the ends of the board as it feeds through. I play it safe and keep my extension tables slightly lower than the conveyor table.

   I vary my feed rates. I use very high speed and light passes(about 1/8 turn) for dense and oily wood as it keeps the remp down and really cuts down clogging. For less dense woods I may go slower with heavier passes(1/4 turn). Fast passes are also nice for finer grits as it seems to cut down on heat a bit.

I can't really make any suggestions on your belt. When I set up my 16-32 I set the belt and have never touched it since(been a few years now).

The suggestion to leave a small gap as you wrap the paper is a very good way to go. Try to keep good tension on the paper as you wrap it. When I lock in the paper at the second clip. I will keep my thumb on the paper that is wrapped on the drum to make sure it stays tight. Then I feed the paper through the clip(holding the clip open) and tug it down(pulling side to side a little to seat it well). Then I release the clip and paper. Run the drum for a second or two, turn it off. Then tug on the paper at the clip one more time. That is about it.

Peace,Rich

I appreciate all the input from you guys.

I'm pretty convinced that the uneven thickness along the length of thicker boards (thicker at the leading and trailing ends and thinner in the middle area) is being caused by flex in the table. I will look more closely at the table and its supports and see if there's anything I can do about that. It may be, though, that experimenting with different feed rates and heavier or lighter passes may yield some better results with that, too.

If any of you guys try thicknessing something thick (e.g. a 3/4" thick neck blank) and measure the thickness carefully with calipers along its entire length, I'd be very interested to know if you get the same results that I do.

I have not seen a need for an infeed table for guitar sized pieces of wood. The main purpose of infeed and outfeed tables is to help prevent snipe, and I've never had snipe. As for outfeed, I have a table there just to catch the wood as it comes out the other side. It is a separate cabinet with a phenolic coated plywood top, which serves as both the outfeed for the 10-20 and an extension table for my table saw. The height of that and the height of the 10-20's stand are very carefully adjusted so that the outfeed surface is just a few thousandths lower than the 10-20's conveyor table.

The conveyor belt design on this machine is certainly far from perfect, but I haven't really found it to be a problem as far as I can tell, whether it's running down the middle of the table or off to one side, or whether there's a little bit of slack on one edge of the belt or the other. With your observations in mind, however, I will pay closer attention to that as well and see if I find any connection between the eccentricities of the conveyor belt and the sanding results.

BTW, running plexiglass through the sander sounds suspect to me. I just use an abrasive cleaning stick, which I CAREFULLY hold against the drum with the drum running. There is, however, a sheet of the same abrasive cleaning material that you can buy and run through the sander. I've seen it at Rockler and other places.

I also just want to reiterate that, although I have been having some issues with the 10-20, I still like it a lot and have generally been impressed with its capabilities. I would still recommend it to other guitar makers who either don't have the space or the funds for something like a much larger drum sander or a wide belt sander. The only larger drum sander I've ever used is the one in Sergei de Jonge's shop (I forget the brand, but it was much larger, not open-ended), and I honestly don't find any significant difference in the capabilities of this little 10-20, except for having to pass wide pieces through twice, and the resulting issue I'm having with the ridge. Otherwise, thicknessing is generally just as easy and just as quick.   

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

I'm a known fan of the little 10-20. In fact I'm on my second one! I traded up my first, which had worked faultlessly, for a 16-32 and had no end of trouble getting it to sand evenly, it seemed to have much more flex than my beloved 10-20 .

Anyway I sold the 16-32 on to someone else and let them have the frustration. For a couple of years I did without one at all until a kitchen fitter friend of mine gave me a 10-20 (I'd let him cut a lot of wood up on my big bandsaw). The 10-20 had been used for about an hour when he gave it to me, he had bought it for one job to use on site (his kitchens run in the $30k-$50k range).

Anyway yet again the 10-20 has performed flawlessly for me once I set it up. I adjusted the drum horizontal, I used some 1" steel stock, and it hasn't produced a ridge of any sort. I do have it bolted onto a 2" thick base, on a heavy wooden trolley so that I can move it around, which I think helps keep everything straight and square. I don't use an infeed table but I do use my island workbench for outfeed. I do put a lot of stock through it on a 1" MDF carrier with 120grit paper on it, this gives very even in and outfeed with no tendency to tilt.

I do use it only as a finishing sander which is what it was designed for.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Colin, thanks for weighing in here and sharing your experience.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

I too have one of these machines and have not been very pleased with it. I find it rather underpowered. My biggest gripe is with the conveyor belt. No matter what I do it consistently moves to the left, until after about every four passes I have to stop everything, loosen it and move it back to the other side. Quite a pain.

As for two-pass sanding, in the end I've found it best to thickness top and side plates before joining so everything contacts the drum in a single pass. It's much more difficult to join very thin plates, but not impossible.