Building a Stroke Sander
Craftsmen share tips about making and running this handy shop tool. October 2, 2005
Question
I just finished building a stroke sander for flattening tabletops. I was told that graphite cloth is used under the hand block to reduce friction against the cloth sanding belt. It will turn the belt and wheels black, I'm told. I'm worried about getting graphite on the woodwork. Are there other options? I'll only use the machine once or twice a week.
Forum Responses
(Furniture Making Forum)
From contributor T:
One shop I know uses a product called UHMW plastics. Another uses hard maple. Don't know which is best. I would like to see a picture of the sander you built, as I am looking at building my own.
From contributor E:
For over thirty years I have used a stroke sander in my shop. With it, I have used a graphite back sanding block and never had any problems with black on my work or belts. Maybe someone has tried to use pure graphite on the backing, but what I use is impregnated into the cloth. You want to use a forgiving material on the block or you will have sanding lines in your work because of the tendency of tipping the block when moving it back and forth. My machine was purchased new from Canada in the early 80's. Before that, I made one and used it for 10 years.
From contributor R:
I've been using stroke sanders for 35 years on metal and wood and you have nothing to worry about with the graphite. It's the same graphite found in a common pencil. Put a 1/4" pad of firm felt between the handblock and graphite for best results. Some lead shot in the handblock will make for less fatigue in using the handblock. If you slip and touch the graphite to the wood, it will sand out easily, but it's easy not to have it happen in the first place.
From contributor J:
Where are you getting the graphite impregnated cloth at? I recently purchased a used Mattison stroke sander, but have yet to set up. Will need to make a block, but I can't find cloth. Also, what size motor are you all running? The motor I took off mine was, I believe, a 7 1/2 hp, but three phase and I want to go to single phase. Also, if anyone knows of the best belt speed, I would like to hear. I'll be running a 6" x 340"-359" belt because I got two pallets of them with the sander.
From the original questioner:
That's a monster! 15' long! From my research, most stroke sanders are 5 hp and up. Most belt speeds are in the 3-4,000 fpm range. My shop-made stroker is set up for 1300 fpm right now, with a 3 hp single phase motor. I don't completely trust my machine shop skills just yet. Graphite cloths, sold by the yard, from Grimes Industrial Supplies.
From contributor J:
It's not that big! Sanding belt goes across bottom two pulleys, then up approximately 2' to idler pulleys. Actual table size is only 6 1/2 feet. I bought it from irsauctions.com back in the spring for $150. When I went to pick it up, the man doing the demo of the equipment said he was told to throw the two pallets of sanding belts in the dumpster and I could have them if I wanted them. Who am I to say no? Came home with approximately 250 new 6" belts in the box, and probably another 50 new out of boxes. Also had about 150 6" x 130" belts for an edge sander. Can't find one that they'll fit, so I am building one with oscillation. Thanks for the info on graphite - I hope they have pieces for sander platens as well.
From contributor S:
I have never used graphite, only felt - a basic carpet underlay felt or better white stuff around 3/8 inch thick. I prefer the give in this material and get no blackness. I rub a bit of candle on the felt now and then, especially after installing a new belt, which I cut, overlap and glue myself with PVA, having ground down the grit a little on the overlap.
From contributor R:
The link below sells graphite cloth and has the best price on custom belts with the lowest minimum order. Proengcorp.com is most likely the one making it in the first place. Been dealing with them for over 35 years. You can't get a better pad than putting 1/4" firm felt under your canvas and using lead shot to weigh the pad down. I've used most every type of stroke sander from a hand type with graphite mitts (talk about hand sanding with a machine), handblock stroke sanders, fulcrum pad stroke sanders, to double belt through feed automatic stroke sanders. Even metal shops doing sheet metal and cast signs use stroke sanders to this day.
From contributor R:
I know the Mattison stroke sanders quite well. I set one up in a metal fabrication shop and recommend you use a static converter to get the best bang for your dollar. The slight loss of power is negligible versus the cost of changing motors. Finding a single phase motor to mount the drive drum is cost prohibitive compared to a static converter. I've set up three of these Mattisons over the years and they are one of the best stroke sanders out there for a handblock type. For the metal shop, I picked a Mattison that was sitting outside of some guy's shop. He got it for free but was having a hard time selling it because no one knew if it was missing pieces or worked. I picked it up for $700 with no questions asked because I knew everything about it and could get it running even if the motor was shot, and the motor was fine. I can guarantee that Grimes is getting their graphite cloth from www.proengcorp.com.
From contributor J:
My sander does not have the motor built into the drive wheel. I also got a folder of quotes from Mattison to the company that originally bought this machine that show several types, including direct drive. Mine is belt driven, motor sets on floor. I am debating on buying a used wide belt for my small, part time cabinet business to do
cabinet doors and parts. In your opinion, how well does the stroke compare to a wide-belt? Can't decide if I want to go the expense of the wide-belt, but I have never used a stroke sander before, either. That's the reason I haven't set it up yet; that and I don't have room - I will have to add on to shop.
From contributor R:
Sorry about the assumption on the motor. All the ones I've seen were direct drive. I still think it's cheaper to use a static converter unless you can pick up a motor real cheap. A few hundred bucks at www.use-enco.com. Contact www.phase-a-matic.com for tech details, but enco has good prices.
All the shops I've worked in had both types of machines. The wide belts and stroke sanders overlap in some areas, but there are some things the stroke sander does better, such as sanding cross grain scratches out on frame and panel doors - things wider than a widebelt, of course. Belts are a lot cheaper, but it does take up a lot more room. It takes a bit of practice to learn, but it's not that bad, plus you can pick up these machines for a song compared to a wide belt. I personally like them a lot and I've used wide belts a lot, as well. I've been doubly fortunate to have experienced both machines in the metal and wood industry and don't think the stroke sander will ever be obsolete. In one shop, we had three types of stroke sanders, handblock and mitt, air fulcrum with adjustable felt pads, and a double belt through feed automatic. We used them and the wide belt equally.
From contributor B:
I recently purchased a 6 ft progress and it is powered by a 3hp Leeson 1 phase motor, belt driven. Seems to have lots of power. The motor is the one that came from the factory. They are a great addition to a small shop.
From the original questioner:
Thanks for all the great information. The 3 hp is getting swapped out for a 5 hp today. I've got small forklift wheels mounted on light trailer stub axles to carry the belt. They are a bit heavy. Gets hot too fast and I could stop the belt if I sanded hard enough. The graphite friction cloth is fine - it's not as dirty as I thought. That's a real money saving tip about making your own belts!
After all this work, I'm not sure this is such a good way to flatten solid wood tabletops. Seems better for finish sanding. I have 100 grit belts, will try 40 grit next. I want it to do some abrasive planing. Can't afford a 50" planer/drum/or widebelt.
From contributor J:
Do you also have a wide belt sander? If so, how does the stroke compare? I'm looking for some insight on the best way to use a stroke sander for sanding
cabinet doors. What grit belts? I understand the motions used, but how about the speed at which you move table or pad? I know this is something that could be learned in a couple of minutes watching, but is hard to describe in words, but I have never been around a stroke sander. I am trying to decide if I want to set this one up or bite the bullet and buy a small widebelt, which is really out of my budget and exceeds the electric capabilities of my shop.
From contributor R:
You could start with 100 grit... depends on how much you are sanding. Move briskly and evenly. Push the table in and out as you move the handblock side to side. Tread lightly on crossgrain, as it sands much faster than sanding with the grain. Last thing I do is rotate the door 90 degrees and remove most of the cross grain scratches on the rails. A light touchup with a random orbit sander finishes it up. The making of the handblock is more critical than you think. I learned from a 30 year veteran and it takes a good afternoon to make it correctly. It takes careful grooming of the slightest pitch and knocking the corners off keeps it from digging in.
From contributor J:
Contributor R, could you post a picture of your handblocks and give any tips for making them?
From the original questioner:
My stroke sander works better than I expected, but will need to be ducted into a DC system next. Also will be adding a sanding disc to the pulley wheel via lug nut extensions.
From contributor R:
Subject to interpretation. Start with two pieces of 3/4" plywood and chamfer the corners about 1". Hollow out the second one and attach it on top of the unhollowed one. Fill the void with lead shot, put a 1/4" luan cover over it and attach a handle. Glue the 1/4" felt to a piece of cardboard and make it fir the handblock. Next, groom the felt so it has a slight hump of almost 1/16" higher in the middle. It will compress over time and can be touched up. Wrap graphite cloth around the block and felt and staple it to the sides of the block. The graphite will wear and have to be replaced in time. One test is to take an old belt and stained panel and use the handblock to see how evenly it works. There's a big difference between a handblock with just graphite and one with felt. Without the felt, it's a more uneven, less controlled finish. The chamfered corners keep it from digging in. It takes some experimenting but is well worth it. I learned the subtleties from a 30 year veteran and it changed my approach to making handblocks. I've used another version in metalworking that used a solid chunk of graphite in a technique called "blocking out." Only useful for doing metal, as it levels the material instead of floating over it like you would for wood. Totally different application and desired finish.
