Replies

1. 
   RickL | May 01, 2009 02:38pm | #1

   You do realize you will have to hand sand or random orbit sand to remove the ripples left by  the drum. Like a planer a drum snader leaves a machine mark even though most folks would never realize this.  A drum sander is not a finish sander in the sense you can go right to finishing, especially if you are staining the wood. Widebelts have a platen which will give a true finish sanding that can go right into the finishing room. The other preferred method is a stroke sander.  220 is much to fine for a drum sander in my opinion and experience.

   
   

   ---

   Edited 5/1/2009 8:41 am ET by RickL

1. 
   MikeHennessy | May 01, 2009 02:42pm | #2

   "You do realize you will have to hand sand or random orbit sand to remove the ripples from the drum."

   OK. The first time I read that, I was thinking you were telling him to take a ROS to the sanding drum to remove the ripples and make it smooth.

   ;-)Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

2. 
   lignumvitae | May 01, 2009 03:42pm | #5

   RickL,

   I understand your thoughts.  It's nice to use the drum sander to even out any joints such as when assembling a bookmatched piece or making a wider board of several.  Even with a well made glue joint some pieces don't match up perfectly.  The old hand sander can get the job done.   The ripple caused by the drum sander is minimized with micro passes but it is still neccessary to finish with hand sanding.

    

   Thanks for your input.

1. 
   RickL | May 01, 2009 05:30pm | #7

    It's nice to use the drum sander to even out any joints such as when assembling a bookmatched piece or making a wider board of several.  Even with a well made glue joint some pieces don't match up perfectly. 

   If you use the curved caul technique for gluing panels you won't need to deal with that issue. I have glued up 4' x 8' panels with perfect registration and only have to sand the planer marks off the panel. I always mill my stock to the finished dimension before glueing the panel and only have to give a light finish sand to remove mill marks. I have access to widebelts sanders in friends commercial shops but never need to use it.

    

1. 
   lignumvitae | May 01, 2009 08:10pm | #9

   Rickl,Thanks again for your ideas and advice.

3. 
   brownman | May 02, 2009 06:14pm | #10

   Rick, I know we've been through this before but my wide belt without a platen is still not leaving any machine marks on finished pieces. I've been using this wide belt for several years now and have never had to do any hand sanding to remove any marks. Grizzly 18" wide belt. Apparently this isn't true for all wide belts without a platen.

1. 
   RickL | May 02, 2009 07:05pm | #12

   I would have to disagree. If you had a platen on your machine you could sand a piece with the platen engaged and then sand a piece with platen disengaged. You would notice a difference in the finish, more so with a dark stain. I've been using, repairing and tuning all kinds of sander in commercial shops, including stroke sanders, drum sanders, profile sanders and widebelt sanders for 35 years. If what you have works, great! If you haven't used a platen widebelt it's impossible see the difference, but it's there. The other advantage to a widebelt over a drum sander is the oscillation of the belt. Drum sanders leace a more linear finish and the oscillation breaks the line up which gives a nicer finish. The size of the drum makes a difference as well. Many of these sanders are also used in metal work where the difference is more noticeable than in wood. Until you have tried all the sanders in other mediums it's really impossible to see the differences. Therer is no difinutive book on the subject nor have any of the hobby magazines really even touched upon the subject in any depth. It would be good to see an article comparing the drum sander, widebelt with and without the platen and the stroke sander. That would be very informative reading to say the least. Stroke sanders are one of the best sanders for the small shop as they are inexpensive but do take up more room.

1. 
   Lataxe | May 02, 2009 07:27pm | #13

   Rick,

   My own experience goes along with what you say; but I only ever used one near-bottom-of-the-market drum sander.  Even with a 240 grit loading it leaves very fine parallel scratches that can be seen in a raking light; and appear more obvious when a film finish is applied.  However, such scratches are very shallow and come out with a very small amount of RO sanding. 

   Mind, the coarser the grit the deeper those scratches. 

   I know 240 grit is generally reckoned too fine for a drum sander but if one is merely sanding out fuzz or very shallow tear out from wood already thicknessed in the planer, or sneaking up by 0.2mm to an exact thickness for stringing, 240 grit leaves the best finish and doesn't require endless passes as only a tiny amount is being removed.

   I can imagine a better-engineered sander than mine minimising those parallel scratches.  In fact I was reading somewhere about (I think) a newly available Jet drum sander that also oscillates the drum side to side, which is claimed to avoid scratches altogether; and to leave a surface ready for finishing.  Of course, advertising claims are one thing and reality sometimes another.  :-)

   Lataxe

2. 
   brownman | May 02, 2009 09:17pm | #14

   I too think an article comparing the differences in finish between drum and wide belt sanders may be an interesting read and might help those trying to decide which to purchase. A few weeks ago I built a new cabinet for one of our bathrooms and made the face frame from poplar. I sanded the pieces on the widebelt to 220 then stained it with an alcohol based black dye stain. Then sprayed about six coats of clear finish after which I sanded it progressively from 600 down to 1200 with wet and dry sand paper. Then I buffed it with 3-M perfect 3000 rubbing compound to a super shinny high gloss finish. I did this so the finish would flow in with the black granite counter top. It turned out very nice. The point though I'm trying to make here is that even with a dark black stain I still haven't seen any machine marks left by my wide belt. And this stain wasn't so black that you couldn't see the grain of the wood. So my wide belt, without a platen, is working for me and I'm glad cause these machines aren't inexpensive. A stoke sander for me at least would have taken up more space in my small shop than my 18" wide belt so I'm glad I went this route.

   Edited 5/2/2009 2:18 pm ET by brownman

3. 
   gofigure57 | May 03, 2009 02:52pm | #18

   RickL,

   Questions here on the platen.  I have a 25" 1985 Sandmax  wide belt sander, this model has two sanding heads driven by a 15 hp on the front head and an 11hp on the rear, both 3 phase. The rear sanding belt has an adjustable platen. I use this machine for final dimensioning of lumber , flattening small stock, ect... 

   My question is what dose the platen do and what should I look for when adjusting it . I have been using this machine for 15 years now, it was in the shop when I  purchased the shop and the contents.  The platen adjustment was never explained to me.  

   The finish off the sander is quite nice, when I hold the board up to the light what I do see is a wavy sanding pattern created by the oscillation of the belt . This pattern dose not bother me as light sanding or hand scraping clean it up quickly. 

   What combination of belt grits do you feel would yield the best results with this type of sander?    

   
1. 
   ring | May 03, 2009 03:45pm | #19

   That's a nice machine for a home shop. I'm sure that Rick will answer your post, but I'll give you my 2 cents as well.Typical belt combinations might be 80 and 120, or else 120 with 150.
   Of course it depends on what you're sanding. If you're gluing up veneered panels you can send them thru that sander as well, but I'd use something more like 150 with 180 grit for that.I'm not familiar with your specific machine (the one in our shop is an SCM). But it's the platten that should be doing the final sanding, not the drum, so it should be adjusted accordingly. Mine is covered with a hard felt material which needs to be replaced from time to time. If you tend to feed material mostly in the center, the felt eventually wears thinner there and you cannot get a perfect finish across a wide piece.David Ring

   http://www.touchwood.co.il/?lang=e&id=1

2. 
   gofigure57 | May 03, 2009 03:56pm | #20

   David ,

   Thanks , what I have on there now is 80/120 grits.  Like I stated the finish is not bad , I am just curious  as to the capabilities of the machine.

   Tom.

3. 
   RickL | May 04, 2009 01:45am | #21

   The platen will make a huge difference in the finish. Standard is 1/4" felt with a covering of graphite cloth. It should be set about .010" under the last drum. There should be a lever crank so you can pull the platen up higher than the last drum for general sanding then you can drop it down for the last couple of passes. You shouldn't even have to move the table higher. You should be able to notice a difference in the finish between the drum and platen engaged. With the platen you won't need to hand sand and can go right to finishing. 80 and 120 grit or 100 and 150 grit. Don't skip too many grits as it will have a harder time removing rough scratches. No Manual???? I'd get a manual from another machine to get some basics. Surprised no one in your previous shop knew anything about it. Show how many folks don;t even come close to maximizing the potential of their machines.
   You have a nice machine that's capable of better finishes than you have ever experienced.Felt can be gotten from http://www.mcmaster.com
   Been buying graphite from these guys for 35 years http://www.pecfrictionfighters.com/product-categories.aspx
   Call them to pick out the right graphite.

4. 
   gofigure57 | May 04, 2009 02:57am | #22

   Thanks Rick,

    Great Info,  I think I might have the manual I will have to look for it .  the machine has been pretty much bullet proof  the only repairs have been from a maintenance standpoint , New belts and re hosing the pneumatics as well as greasing fittings. Thanks for the links you have been very helpful.

   Tom.

5. 
   RickL | May 04, 2009 12:27pm | #23

   Good luck and if you can post some pictures on the difference between platen and non-platen sanding to show others the difference.

6. 
   gofigure57 | May 04, 2009 01:42pm | #25

   Will Do.

7. 
   gofigure57 | May 05, 2009 02:16pm | #27

   Rick ,

   I found the manual, oddly enough there is no info on the use of the platen in there or how to remove it.  There is a exploded view of the platen head, thats it . 

    Anyhow after some inspection and probing around I determined that the actual platen slides out on a sliding dovetail way, no bolts nada.  I really did not think that this platen has ever been maintenanced and was surprised that with a little coaxing it slid out fairly easy.

   You are correct in that it appears to be 1/4 felt  wrapped with graphite paper. The wear and tear on it seems to have rendered it ineffective.  Time to order parts .   Once again Rick your knowledge has been invaluable, thanks I will keep you posted.

   Tom

8. 
   RickL | May 05, 2009 02:56pm | #28

   Typically the 1/4" firm felt is double stick taped or held in place by the wrapped graphite cloth. Typically there are 2 metal strips with holes to secure the grahite canvas.  The aduster for the cam should have a lever to bring the platen just above the drum so you would be using the drum and then you can drop the platen down just below the drum for platen sanding. Make sure you can do this. Since it wasn't maintained you may have to adjust the cam to get the correct up and down movement.  This platen will allow some sanders to sand veneered plywood. The better machines have a air floating bed to make this even less likely to sand through the veneers.

   You would sand your material with the drum then bring the platen down without changing the table setting for the last couple of passes. The surface will be done and able to go right into finishing. You will notice a difference in quality if your platen is done correctly.

9. 
   gofigure57 | May 06, 2009 02:33pm | #29

   Hi Rick,

   Here are some pics . I will check today on the platen adjuster.

   Edited 5/6/2009 7:33 am ET by gofigure57

   
10. 
    RickL | May 06, 2009 04:09pm | #30

    Rebuild the platen and reinstall. Get some kind of indicator between the table and 1st roller on the second head and compare the height of the platen to the first roller. Make some kind of marks on the platen adjsuter so you know when it's above the roller and below the roller. The secon roller on the second head should be higher than the first roller on the second head as well as the highest platen setting. It's pretty logical when you get the concept.

2. 
   Lataxe | May 01, 2009 03:11pm | #3

   L,

   There are a number of timbers whose content doesn't like the heat generated by a drum sander at the point of sanding.  As you have experienced, it's very difficult to avoid heat from drum sanding even with changes of feed rate, various grits and depths of "cut".  It might be posible if the drum speed could be slowed but I'm not sure that any of the drum sanders available have variable drum speed (although they allow chages to feed belt speed).

   Some of the exotic timbers have oils, gums, resins and sugars within them that are very sensitive to heat.  You may have found that such timbers also burn much more easily on the TS or with a router, if one dwells over-long with the cutters in one spot.  Happily it's possible to lessen the genrated heat with cutters, by taking smaller cuts, more rapid passes or using less teeth (on the TS).  There seems to be no equivalent technique for reducing drum sander heat enough to avoid burning those more sensitive exotics.

   More common timbers such as oak and cherry can burn in the drum sander too; but less readily than many of the exotics. In these cases an increased feed speed and a lighter cut with a coarser grit does seem to avoid burning, unless there is a section of oak with a lot of sugars in it or a bit of cherry with a lot of gum.  Areas around knots are often problematic, especially as they are hard and can slow the feed belt momentarily.

   Some timbers create charred deposits on the sandpaper in an instant, which are very dififcult to remove.  I once ruined a whole sanding belt with just a few inches of tambooti.  Sometimes (not always) such charred deposits will soften and scrape off with something like CMT orange cleaner, without harming the sand paper.  This is a tedious process though.

   Lataxe

1. 
   lignumvitae | May 01, 2009 03:36pm | #4

   Lataxe,

   Thanks for your thoughts, more insightful, than others I have talked with.  I guess I am back to the thickness planer for precision dimensioning and then the hand sander.

    

   Thanks

2. 
   philip | May 04, 2009 01:35pm | #24

   'Ere, Tamboetie, hey?
   Now that is a princely timber hardly deserved by those wasters south of the Limpopo.
   Now , more importantly, how did you come by the stuff and how much do you have?
   I can think of few timbers better, very few, very very few. On no account should you use it for a braaivleis....Any Bushman or Hottentot will tell you that.I have a small piece left , measuring aproximately 400mm x 75 x75 - possibly to use for another batch of mini planes if I can bring myself to cut it up.
   I made a knob long ago for the very plane pictured-my trusty Record #51/2, third from front.Note the chatoyance.Philip Marcou

   
1. 
   Lataxe | May 04, 2009 02:51pm | #26

   Philip,

   I got a first chunk of tambootie (tambuti; tam-etc.) from John Boddies woodstore in Borough Bridge, Yorkdhire when their wee shop in the midle of the vast timberyard had the attached warehouse chocka-block with near 150 species of timber, including many exotics, in plank-form.  Each plank was individualy priced and it was easy to spend too much.  However, it was wunnerful for rooting to find small pieces of stuff like tambooti, ziticote, African blackwood and similar. 

   Alas, the warehouse is now mostly given over to wooden flooring with a very much reduced set of planks for sale.  Tambooti, snakewood and such are no longer to be seen.

   I did find another chunk 300mm X 75mm X 75mm amongst the timbers for sale by a-one o' them turning suppliers.  Again, one pays far too much for the stuff in chunks sized for the lathe.  Nevertheless, I could,'t resist.

   Since then tambooti seems to have disappeared from the British market, although I bet that Richard Jones knows of supplies here or there.

   Mine became various small boxes, of which I only have one myself; the daughters got the other two, one of which got lost in a to-fro journey involving her 2-year stay in Oz.

   I enjoy not just the grain, the subtle dark hues and the interesting whitish sapwood shot with red and black threads but also the smell of the stuff - especially when first cut.  Like the best exotic perfume you ever put yer nose to.  It does linger inside the box I kept although it's now very faint.

   Lataxe

3. 
   BOBABEUI | May 01, 2009 04:12pm | #6

   Lignum,

   I own a Woodmaster 2675, it's a really nice machine, but as you have discovered drum sanders are really finicky beasts. I have only run typical domestic hardwoods like Walnut, Cherry and Poplar though the beast, I would think with the exotic woods you are using would definately make life more challenging.

   220 grit sandpaper sounds way too fine for a drum, I think the finest that I even own is 150, typically I use 120 or 100. I know you said you take micro-passes, I would say a pass of ~ .010 is a proper pass, the one time that I attempted to tweak just a little more, I burned the 120 grit paper pretty bad. I would think the finer grits also generate more heat or have less ability to dissipate said heat.

   Dust collection is pretty important, not so much for the obvious reason (to keep the dust down) but also to keep the paper clean so it doesn't burn.

   Hope this helps..

   
   

   ---

   Edited 5/1/2009 9:13 am ET by BOBABEUI

1. 
   lignumvitae | May 01, 2009 08:09pm | #8

   BOBABEUI,Thanks for your thoughts. It appears the universal thought is to stay away from sugars and resins.

4. 
   brownman | May 02, 2009 06:27pm | #11

   I have planed cocobolo on my wide belt sander with the same results as you. Lataxe is correct in that most exotic hardwoods have to much oil or resins in them and generate to much heat to be able to successfully sand on a wide belt or drum sander, without ruining the belt. I went one worse when I tried sanding a 3" wide pieces of aluminum. It sanded it with great effort but after a few passes it generated so much strain on the motor that it fried my starter motor capacitor. Plane and hand sand is all you can do with these types of hard wood.

1. 
   lignumvitae | May 03, 2009 03:18am | #15

   Brownman,

   Thanks for your thoughts.  My original inquiry about the drum sander has created a fair amount of discussion which I find very useful. 

   Interesting side story.  I have a Ecogate system that turns the dust collector on and off automatically by sensing vibration of the running machine - with 8 electric gates now in use.  Some machines run 'quiet' as did the drum sander, that is not enough vibration to send the signal.  Therefore my first run with the sander, I didn't have any experience yet, resulted in no dust collection, dust piling up in the machine and ultimately a blown out paper and lots of smoke.  The lack of vibration is solved with a toroidal senser which measures current flow.  I have two of them in use, the other on the table saw.

    

   By the way, I love the Ecogate system.

   L

1. 
   brownman | May 03, 2009 08:57am | #16

   I had given some thought about using the Ecogate system but haven't decided weather I want to go that way. Not sure that I can as I'm changing all my machine ports to five inch for better airflow so I'll be using all 5 or 6 inch blastgates. I purchased a Grizzly 3 HP cyclone system about 4 years ago and believe it or not just got it set up about six months ago and just last week was able to purchase all the spiral ducting and fittings. So I'll finally be setting it up this next week. I didn't want to go with the less expensive ducting so it took awhile to afford everything since it wasn't on my highest priority of tool purchases. I bit the bullet a little over a year ago and bought a panel saw so I wanted to pay that off before I finished off my dust collection system. Up to this point I've been using a smaller roll around 1 1/2 horse dust collector with a pleated filter which has done Ok, but without the cyclone the filter tends to clog up pretty quickly and it's a huge hassle to always be changing the hose from machine to machine.

5. 
   WillGeorge | May 03, 2009 01:24pm | #17

   I use my littller in width drum sander just to level things off.  Hand sanding from there!