Drum sander precision

[scott vroom]

How precise are drum sanders? On my 15" planer, once the depth is set and the posts locked I can rely on running multiple boards planing to the exact same thickness. Can I expect the same result with a drum sander? BTW, I'm looking at the Grizzly G0458 18/36 drum sander. Are the open end models as consistent as the closed type? I build lots of face frames & rails/stiles and need the surfaced boards to match exactly in thickness.

[Chip Lindley]

Scott, varied results have been reported here with open-ended drum sanders, depending on Brand.

With my former Grizzly 1066 24" DDS, and my current Woodmaster 3875 DDS, I have never had any problem with thickness inconsistencies. The felt drum covering of the Griz, and the Velcro covering of the WM drums helps even things out without noticable "snipe".

Problems would arise if the conveyor table is not coplanar to the drum from side to side. That would show up more on wide panels than narrow pieces. But there is an adjustment procedure in the manual for that.

After assembly of doors, or FFs, I touch up corners with an ROS. I never run completed units through the DS because of cross-grain scratching.

[Cary Falk]

I have the G0458 and do not have any thickness precision problems. The drum and the table are solid and do not flex. Sometimes if the handle is between 6 and 12 o'clock it wants to move down to 6 o'clock due to the weight of the handle, some of the maching vibration, and pressure against the table I guess. I have thought about rigging up a table or wheel lock to fix it, I just never got around to it. It is not a big deal but it does try to move a little bit. I just got done sanding four 2"x2" table legs. They came out just fine.

[Peter Quinn]

I have a performax open ended sander and it's very consistent end to end, within a fee thousands anyway. I can't speak for the Grizzly but would expect similar results. The issue with a sander is that there are several variables which affect the end result. Wood can be more or less hard board to board, and the sander has different grits of paper which can be used, variable feed speed, and variable depth. If too much dept is taken per pas at too high a feed speed with too high a grit, things start to get a bit inconsistent. One board may give up more thickness per pass, or there may be soft spots in then paper or feed belt that cause less materialmto be removed if theynare excessively compressed. A planer will leave every thing the same thickness because the relationship between knives andniron bed is fixed. But there is flex built into ANY sander, even a large industrial wide belt. I use a wide belt at work regularly and while it's far more powerful than a drum sander, it can still be usedmin a manner that produces inconsistent results. dAMHIK!

So take it light with a sander and dont rush. I took me a while to understand my sander and develop a relationship with it's capacity. It's one of those machines where the operator's settings greatly influences the end results.

[John Grossi]

Scott, I have a newer Jet 16-32 (performax). I would consider this machine to be very precise. Of course setup is extremely important. I can run multiple pieces thru and be within a few thousands. I have done rails and styles seperate, and have sanded them as a completed unit. Either way a touchup with the orbital is required. I prefer running the completed unit thru because of superior dust collection.

[John TenEyck]

I have a Delta 18 x 36 and have done wide panels, assembled face frames, and assembled frame and panel doors with equally good results. For faceframes and frame and panel doors, I go over them afterwards with a pad sander to remove the crossgrain scratches and they come out beautifully.

For anything less than 18" I just run them through and they come out within a few thousands side to side. For anything wider than 18" I open the gap at the open end a few thousands, as discussed in the owner's manual and mentioned by a previous poster. So your piece comes out crowned a few thousands in the middle. I can't see it, can barely measure it, and it's never caused me any problems. On the Delta the sandpaper sits directly on the machined drum surface with no cushioning backing layer. I don't know if this is better or worse than those that use a flexible backing but I've had no problems. Light passes is key with these light duty drum sanders, especially if sanding cross grain, IMO. I don't use anything coarser than 100 grit, and often start at 120 grit if I only need to remove 0.010" or less. This avoids deep scratches which are hard to remove.

[Bruce Page]

It depends on your definition of exact. I get consistent thickness, within a few thousandths, with my Woodmaster if I take a group of boards and work them together. I could not get the same consistency with my Delta 18/36 without fudging a little.

[george wilson]

The Delta 18" open side sander is what I have. Its top housing is made of 1/8" thick steel,welded securely in position. The conveyor table's 2 outboard height adjustment screws are adjustable. I have mine set so that there is not even 1/4 thousandth difference in thickness per side of an 8" wide piece of wood. That is how wide guitar wood generally must be sanded. I love the rigidity of the sander. Formerly I had 2 different thickness planer type drum sanders,with the knobby,soft rubber conveyors. I never did get their drums shimmed to make real accurate results.

Of course,you must treat a drum sander very carefully,and I do not turn the handle even 1/4 turn between passes. I am also careful to turn the height adjustment handle slowly,lest the cogged belt slip(which I have heard can happen). So far,and for several years,mine has not slipped with the care I use it with.

[scott vroom]

I have a Delta 18 x 36. For anything less than 18" I just run them through and they come out within a few thousands side to side. For anything wider than 18" I open the gap at the open end a few thousands, as discussed in the owner's manual and mentioned by a previous poster. So your piece comes out crowned a few thousands in the middle..

John, what's the theory behind intentionally opening the gap a few thousands on pieces >18" on your 18 x 36? What happens when wider pieces are passed through with the conveyor coplaner to the drum?

[pat warner]

Have seen many TimeSavers that hold better than .003" on 30+" widths.
Sharp belts on well designed machines, good dust collection, + or - .003" is not unusual on 36" tuned machines!

[Ira Matheny]

I have a Performax 25 that I use frequently. I check the finished thickness with a dial calipers. The only difference I can find in final thickness can be attributed to the wood itself. I recently ran hard Maple and Walnut down to 0.050" The Walnut was always .003 to .005 thinner than the Maple. If it were to run the Maple thru an additional time without adjusting the settings, then the Maple would match the Walnut's thickness.

I find a slower feed rate to produce more consistant thickness of the finished wood. BTW, I was using 100 grit medium on the machined drum.

[Zach Callum]

No drum sander is going to give you ready for finishing results, or the same consistency in thickness that you get from your planer. The only parts that I run through the drum sander are glued up panels. Running face frame and door parts really doesn't save any time.

[John TenEyck]

John, what's the theory behind intentionally opening the gap a few thousands on pieces >18" on your 18 x 36? What happens when wider pieces are passed through with the conveyor coplaner to the drum?

If you don't open the gap a couple of thousandths there is a high risk of the outboard edge of the sandpaper leave a ridge in the piece you're sanding. I was curious if it was really necessary so I tried it with everything coplaner. I didn't get a ridge everytime, but most times I did; it could be that the angle of the work to the drum has an influence, but I'm not sure. And when a ridge happens it's quite a bit deeper than you might expect and hard to remove. So now I follow the manual and open the gap say 0.002 - 0.003", and I've never had it happen. Just make sure your sandpaper is installed properly (flat on the drum) on the outboard side.

For the comment that a drum sander can't possibly give results as good as a planer, I'd say, well, it depends. It depends upon how well your planer is set up compared to your drum sander. I have one planer that is hard to get less than 0.003" due to wear, but that's still OK for my needs. My drum sander is usually better than 0.003" when set coplaner. Moreover, the parts coming out of the drum sander have removed the planer snipe, non-parallelity, and planer marks, and are ready for final sanding with a pad sander or by hand.

[george wilson]

As I said,my Delta gives accuracy cross the board equal to any planer. But,I know how to get the most out of it.