*Thanks for this. I love the detail you provided on the major part (drum).* The time you took in assembly to get matching diameters definitely paid off later on balancing and leveling.
Well done Susie! That's been a great project to watch. I built a drum sander 10 years ago when I made ukuleles. Used a wood lathe, kind of half way there with the chuck, tailstock and bed. In the drum truing I just used a full sheet of sandpaper directly on top of the bed. Just pull it in and out against the rotation and slide it along. Simples!😊 It'll be interesting to know if you get any flex with the drum now that you've cut those slots. Those two inner drum sections are now only connected to the two outer drive sections by a greatly reduced glued surface area. Hopefully they won't break away and move on the shaft. Still, a lot better than spending £940 on Axminster's entry level Jet, eh?!
Moistier is always a problem when using any wood. Especially when using MDF. You could overcome this problem with a PVC cover on the outside of the drum and after that closing the two ends fully with a rubber coating or something. Besides that you have an always a flat surface to glue your sandpaper on. Furthermore I love these videos of you. I am making beehives from Red Cedar and that’s a very expensive wood. So every part of that wood is been used even the smallest parts. That’s also why I have a lot of sanding to do. Building such a drumsander would save me a very large amount of time.
With reference to sanding blocks, I use expanded polystyrene packing cut up into small blocks as sanding blocks. I find that it is excellent for guitar sides especially the waist of the guitar, where a small light easily shaped piece is required to get into the contour of the guitar. Anyway as always keep up the good work and looking forward to seeing and hearing the guitar finished.
I think you are correct that temperature is important, but I suspect it's because the moisture more rapidly penetrates the wood. Note that plywood is said to be resistant to expansion because of the crossgrain orientation of the plies. This does not constrain expansion in thickness.
Do you think MDF would be more stable? I have seen it do odd things with humidity too though. I would guess sealing it is of utmost importance. Still wondering about alternative materials...plastics and such that are less prone to movement.
I do wood work both flat and turning and in the last few years metal work. I now appreciate how much wood moves compared to metal, mostly from moisture change. Applying a finish slows down the moisture change but does not eliminate moisture change. I have milled solid hardwood on my milling machine to be flat, and then the next day find it is not quite flat. Your plywood segments expose a lot of end grain. Moisture change happens mostly from the end grain so you may still observe some movement. MDF would be more stable so will keep its dimensions better than plywood, but it awful to work due to the dust. Try looking for some aluminium tube. This should give you a better drum for this application. Dave.
Hi Susan, the way you constructed the drum is the secret to its expansionist tendencies. the RH (relative humidity) has been extremely high lately along with the temps. plywood is far more likely to expand ever so slightly in thickness *because* the veneer layers are so thin. they then become hygroscopic (water loving or sponge like) and will take up water far faster than solid wood can or would. while putting relief cuts into the drum will temporarily relieve the problem, in the long run it will make it much worse as you are giving the humidity additional points of entry into the corpus of the drum. the best thing you could do to accommodate the expansionist properties of your drum is to: one: take the thing completely apart and either varnish the discs on the flat sides facing each other or seal them wax, oil them, boiled linseed oil.. anything to prevent atmospheric moisture from gaining entry into the wood. second: place thin layers of rubber like slices from an inner tube from a tractor or a truck tire between some of the discs. every two or three discs would be plenty. this gives the stack of discs a place to go and press against the rubber which will give somewhat under pressure but then not squish out and cause streaking in the finish. three: take the drum off the shaft and make the slots that the drive screws engage in the drum a little longer by at least 3 to 5mm along the long axis of the drum, that should give the drum a little wiggle room and prevent it from warping or at the very least reduce the warping significantly. the wood won't expand thermally which is why it is actually a really good choice of material for making the drum. the dog screws you have in the shaft which drives the drum itself keeps the wood from going anyplace. in this case it will cause the distortion you're seeing in the drum hope that helps a little cheers mike
When something like a washer is heated up the hole in the middle gets bigger. Perhaps his also happens when wood expands due to increased humidity? That might allows the discs to move off centre?
I can't find the videos on how the drum sander was made. I have made my own drum and the one thing I hadn't considered was expansion joints. I used MDF to make my drum and I am not sure if I'll have a problem with expansion. But if I do, you've shown me a way to alleviate the problem. THANKS!
I know absolutely nothing about building one, beyond your example and one other, but could you have used PVC pipe and connectors instead? Maybe plywood at the ends where the sand paper has to be started and ended but moisture resistant PVC in between. Or would the RPMs tear that apart? Thanks
A great series, Susan! I'm considering building a drum sander myself, and not only does yours seem to be one of the best designs I've seen, your trials and tribulations along the way have been very informative as well. How has the sander and drum held up in the 18 months since this last video was released?
I have recently discovered your channel while researching DIY drum sander videos. Congratulations, what a marvelous presentation. Your project was well thought out, care-fulling designed and skill-fully assembled. May I add one suggestion? The addition of two rubber wedges (one each side of drum) might assist you in stabilizing the drum and freeing your hands so that you can tighten the sand paper. A couple of door wedges?
Kevin below is correct. Not only did the heat of summer have an effect but the heat generated by sanding will also create stresses so it is important to allow those stresses to dissipate. By only locking the drive side bearing to the shaft will allow it to 'float in the non drive side and relieve this problem. You have in effect locked all this stress between the two bearings with nowhere to go.
Hi Susan. How has your drum sander held up with time? Did cutting the expansion slots cause further trouble (e.g. by increasing moisture ingress route)? I wonder if using marine grade plywood would have prevented the expansion problem?
The expansion/warpage might have been less when you'd have used MDF. That has a far more random fiber orientation. Another decision that exacerbated the untrueness of the drum is using sandingpaper or web directly on the drum. Using velcro hook band glued to the drum with velcro sanding paper gives a cushioning effect evening out the sanding and giving a more effect allthough not as predictable in thickness. More of a sneaking up to the intended thickness way of using the machine. Cheers, Dick van Zanten
My thickness sander is very similar to yours and to Pat Hawley's, which is documented at Matthias Wandel's website. The drum is made up of 3/4" thick plywood disks that are all glued together. The disks are not glued to the steel shaft. They are free to slide along the length of the shaft. I drilled a 1/4" diameter hole in the shaft and inserted a 4" long steel rod. I routed a cavity in one of the disks to contain the rod. The rod is the only drive connection between the shaft and the drum. I have not had any problems with the shaft bending or the drum going out of true.
In theory my discs are free to move, at least until they hit the peg/screw at the other end - maybe a millimetre or 2 - as the peg is only constraining them from rotating - it’s not hard against the last but one disc - the last disc was dropped over it, if that makes sense. However they’re so tight against the shaft that I doubt they can move in practise. If the discs were looser I’d worry they could move radially - maybe that’s not such a problem though.
I had another look at the video in which you assembled the drum. It's been some years since I assembled the drum for my sander. To the best of my recollection, I would say that we both assembled the drums, more or less, in the same manner. The fit of the disks on the shaft is about the same for both drums. I suggest that drive screws on both ends of the drum are unnecessary. However, I don't think that the second set of screws on your drum is restricting the expansion and contraction of the plywood disks. I'm using hook and loop sandpaper. It might be that my drum is also out of true, but the cushioning effect of the hooks and loops is masking any lack of trueness. I rarely have to replace the sandpaper, so the added expense of hook and look sandpaper is irrelevant. I'm not building guitars, so I don't need the precision that you probably expect from your sander.
That's just the nature of wood. If you think about the fibers they expand and contract with the weather but they move much more in their width than they do in their length. If you consider your drum, virtually every single grain/fiber is oriented so that every laminate in every ply disk is going to cause maximum expansion along the length of the shaft. The flat pieces like the base along their length and breath will have 1/2 the laminates trying to move while the other 1/2 resist that movement. It's thickness however will expand in an unrestrained fashion.
David Willis I looked up thermal expansion, considering other possible materials for the drum, eg PVC pipe, steel, aluminum, concrete, wood. Plywood is really excellent in this respect laterally, but as you say expansion along the axis needs to be addressed.
Plywood is still wood. As long as it's not sealed it sucks in moisture and swells, when air humidity is greater than the plywood's. It just doesn't warp like wood, because of the structure. The problem in hot spring days is not the heat itself, it is that hot air can hold a lot of water, and when it gets cold at night, the humidity can get to 100%. The slots help, but also make the drum more flexible. That shouldn't be a problem, it may just take one more pass to get to the final dimension.
Susan, only the drive side bearing should have the grub screws tightened. The other end of the shaft should be free to float axialy within the bearing race to avoid these stresses.
David Willis hello David, I think if the shaft is that loose it is too loose and tightening those 2 grub screws will produce eccentricity to the rotation of the drum.
kevin sumner, the grub screws would easily take up 0.5 or 0.25mm slack which would be enough to cause major problems during sanding. Given that Susan trued up the drum before fitting the glass paper that problem was cured before it was even noticed.
Hi Susan, I know you have made a wooden drum, but have you looked at the "stumpy nubs" sander. He used a heavy duty PVC pipe for his and even made his so that you could have lots of different grits of sandpaper. it might be the perfect answer to your problems.
By 'we' do you mean us? Minor point but I think this is your problem. There is a Canadian company that provide a great drum setup...... When I made mine the velcro fitting of paper was great and the whole kit was stable and my workshop had great fluctuations...
I don't know if you still read your comments at this late date. But I had attempted to make a drum sander with not such good results. I ran into your video's and thought, it is a better design than what I had tried. I'm also glad for this "final video" and all of the others so I can avoid the problems you ran into. Your video's are informative and entertaining. What a treat! Thank you.
*Thanks for this. I love the detail you provided on the major part (drum).* The time you took in assembly to get matching diameters definitely paid off later on balancing and leveling.
Well done Susie! That's been a great project to watch. I built a drum sander 10 years ago when I made ukuleles. Used a wood lathe, kind of half way there with the chuck, tailstock and bed. In the drum truing I just used a full sheet of sandpaper directly on top of the bed. Just pull it in and out against the rotation and slide it along. Simples!😊
It'll be interesting to know if you get any flex with the drum now that you've cut those slots. Those two inner drum sections are now only connected to the two outer drive sections by a greatly reduced glued surface area. Hopefully they won't break away and move on the shaft.
Still, a lot better than spending £940 on Axminster's entry level Jet, eh?!
I didn’t saw all the way to the axle - there’s still a small amount of wood. Also, the discs are very tight on the axle
Thanks Susan, very interesting video series and I learned something in the end. Good job.
Moistier is always a problem when using any wood. Especially when using MDF. You could overcome this problem with a PVC cover on the outside of the drum and after that closing the two ends fully with a rubber coating or something. Besides that you have an always a flat surface to glue your sandpaper on.
Furthermore I love these videos of you. I am making beehives from Red Cedar and that’s a very expensive wood. So every part of that wood is been used even the smallest parts. That’s also why I have a lot of sanding to do. Building such a drumsander would save me a very large amount of time.
Very interesting and thought provoking. Thank you
With reference to sanding blocks, I use expanded polystyrene packing cut up into small blocks as sanding blocks. I find that it is excellent for guitar sides especially the waist of the guitar, where a small light easily shaped piece is required to get into the contour of the guitar. Anyway as always keep up the good work and looking forward to seeing and hearing the guitar finished.
I think you are correct that temperature is important, but I suspect it's because the moisture more rapidly penetrates the wood. Note that plywood is said to be resistant to expansion because of the crossgrain orientation of the plies. This does not constrain expansion in thickness.
Do you think MDF would be more stable? I have seen it do odd things with humidity too though. I would guess sealing it is of utmost importance. Still wondering about alternative materials...plastics and such that are less prone to movement.
I do wood work both flat and turning and in the last few years metal work. I now appreciate how much wood moves compared to metal, mostly from moisture change.
Applying a finish slows down the moisture change but does not eliminate moisture change.
I have milled solid hardwood on my milling machine to be flat, and then the next day find it is not quite flat.
Your plywood segments expose a lot of end grain. Moisture change happens mostly from the end grain so you may still observe some movement.
MDF would be more stable so will keep its dimensions better than plywood, but it awful to work due to the dust.
Try looking for some aluminium tube. This should give you a better drum for this application.
Dave.
Hi Susan,
the way you constructed the drum is the secret to its expansionist tendencies. the RH (relative humidity) has been extremely high lately along with the temps. plywood is far more likely to expand ever so slightly in thickness *because* the veneer layers are so thin. they then become hygroscopic (water loving or sponge like) and will take up water far faster than solid wood can or would. while putting relief cuts into the drum will temporarily relieve the problem, in the long run it will make it much worse as you are giving the humidity additional points of entry into the corpus of the drum.
the best thing you could do to accommodate the expansionist properties of your drum is to:
one: take the thing completely apart and either varnish the discs on the flat sides facing each other or seal them wax, oil them, boiled linseed oil.. anything to prevent atmospheric moisture from gaining entry into the wood.
second: place thin layers of rubber like slices from an inner tube from a tractor or a truck tire between some of the discs. every two or three discs would be plenty. this gives the stack of discs a place to go and press against the rubber which will give somewhat under pressure but then not squish out and cause streaking in the finish.
three: take the drum off the shaft and make the slots that the drive screws engage in the drum a little longer by at least 3 to 5mm along the long axis of the drum, that should give the drum a little wiggle room and prevent it from warping or at the very least reduce the warping significantly. the wood won't expand thermally which is why it is actually a really good choice of material for making the drum. the dog screws you have in the shaft which drives the drum itself keeps the wood from going anyplace. in this case it will cause the distortion you're seeing in the drum
hope that helps a little
cheers
mike
When something like a washer is heated up the hole in the middle gets bigger. Perhaps his also happens when wood expands due to increased humidity? That might allows the discs to move off centre?
So how do commercial sanders overcome this? Different construction?
I can't find the videos on how the drum sander was made. I have made my own drum and the one thing I hadn't considered was expansion joints. I used MDF to make my drum and I am not sure if I'll have a problem with expansion. But if I do, you've shown me a way to alleviate the problem. THANKS!
There’s a playlist ruclips.net/p/PLNZrIoijCmgFgV6tvUMZsj4NNVqyhC3OB
Take the grub screws out of the non driven side pillow blocks to allow for shaft thermal expansion.
I know absolutely nothing about building one, beyond your example and one other, but could you have used PVC pipe and connectors instead? Maybe plywood at the ends where the sand paper has to be started and ended but moisture resistant PVC in between. Or would the RPMs tear that apart? Thanks
A great series, Susan! I'm considering building a drum sander myself, and not only does yours seem to be one of the best designs I've seen, your trials and tribulations along the way have been very informative as well. How has the sander and drum held up in the 18 months since this last video was released?
I have recently discovered your channel while researching DIY drum sander videos. Congratulations, what a marvelous presentation. Your project was well thought out, care-fulling designed and skill-fully assembled. May I add one suggestion? The addition of two rubber wedges (one each side of drum) might assist you in stabilizing the drum and freeing your hands so that you can tighten the sand paper. A couple of door wedges?
Nice idea!
Kevin below is correct. Not only did the heat of summer have an effect but the heat generated by sanding will also create stresses so it is important to allow those stresses to dissipate. By only locking the drive side bearing to the shaft will allow it to 'float in the non drive side and relieve this problem. You have in effect locked all this stress between the two bearings with nowhere to go.
Had u thought of using pvc pipe for the drum with the plywood clamps on the ends
I noticed that you seem to do your work in what appears to be a conservatory? Do you keep the drum sander there? Is it a greenhouse effect?
Hi Susan. How has your drum sander held up with time? Did cutting the expansion slots cause further trouble (e.g. by increasing moisture ingress route)? I wonder if using marine grade plywood would have prevented the expansion problem?
thank you Susan . how would a piece of plastic large plumbers pipe work instead of mdf / plywood ?
You’d need solid plastic. You couldn’t mount a pipe without filling it with something
look at stumpy nubbs on his sander
It would be hard to get a plastic drum true. Eg harder to sandpaper the outside of a plastic drum.
Walter Rider I suspect his shop is climate controlled. Plastic expands a lot with heat.
@@davidhawley1132 It also softens. My dad used PVC for hot water lines in the basement and they sagged between each hanger.
I LOVED the term "BANANOWING" 😘
Haha, I feel like I’ve been watching this drum sander for years now! How long has it actually been?
The expansion/warpage might have been less when you'd have used MDF. That has a far more random fiber orientation. Another decision that exacerbated the untrueness of the drum is using sandingpaper or web directly on the drum. Using velcro hook band glued to the drum with velcro sanding paper gives a cushioning effect evening out the sanding and giving a more effect allthough not as predictable in thickness. More of a sneaking up to the intended thickness way of using the machine.
Cheers,
Dick van Zanten
My thickness sander is very similar to yours and to Pat Hawley's, which is documented at Matthias Wandel's website. The drum is made up of 3/4" thick plywood disks that are all glued together. The disks are not glued to the steel shaft. They are free to slide along the length of the shaft. I drilled a 1/4" diameter hole in the shaft and inserted a 4" long steel rod. I routed a cavity in one of the disks to contain the rod. The rod is the only drive connection between the shaft and the drum. I have not had any problems with the shaft bending or the drum going out of true.
In theory my discs are free to move, at least until they hit the peg/screw at the other end - maybe a millimetre or 2 - as the peg is only constraining them from rotating - it’s not hard against the last but one disc - the last disc was dropped over it, if that makes sense. However they’re so tight against the shaft that I doubt they can move in practise. If the discs were looser I’d worry they could move radially - maybe that’s not such a problem though.
I had another look at the video in which you assembled the drum. It's been some years since I assembled the drum for my sander. To the best of my recollection, I would say that we both assembled the drums, more or less, in the same manner. The fit of the disks on the shaft is about the same for both drums. I suggest that drive screws on both ends of the drum are unnecessary. However, I don't think that the second set of screws on your drum is restricting the expansion and contraction of the plywood disks. I'm using hook and loop sandpaper. It might be that my drum is also out of true, but the cushioning effect of the hooks and loops is masking any lack of trueness. I rarely have to replace the sandpaper, so the added expense of hook and look sandpaper is irrelevant. I'm not building guitars, so I don't need the precision that you probably expect from your sander.
That's just the nature of wood. If you think about the fibers they expand and contract with the weather but they move much more in their width than they do in their length. If you consider your drum, virtually every single grain/fiber is oriented so that every laminate in every ply disk is going to cause maximum expansion along the length of the shaft.
The flat pieces like the base along their length and breath will have 1/2 the laminates trying to move while the other 1/2 resist that movement. It's thickness however will expand in an unrestrained fashion.
David Willis I looked up thermal expansion, considering other possible materials for the drum, eg PVC pipe, steel, aluminum, concrete, wood. Plywood is really excellent in this respect laterally, but as you say expansion along the axis needs to be addressed.
Plywood is still wood. As long as it's not sealed it sucks in moisture and swells, when air humidity is greater than the plywood's. It just doesn't warp like wood, because of the structure. The problem in hot spring days is not the heat itself, it is that hot air can hold a lot of water, and when it gets cold at night, the humidity can get to 100%. The slots help, but also make the drum more flexible. That shouldn't be a problem, it may just take one more pass to get to the final dimension.
Susan, only the drive side bearing should have the grub screws tightened. The other end of the shaft should be free to float axialy within the bearing race to avoid these stresses.
kevin sumner presuming that the shaft is a snug/tight fit in the bearing
David Willis hello David, I think if the shaft is that loose it is too loose and tightening those 2 grub screws will produce eccentricity to the rotation of the drum.
kevin sumner, the grub screws would easily take up 0.5 or 0.25mm slack which would be enough to cause major problems during sanding. Given that Susan trued up the drum before fitting the glass paper that problem was cured before it was even noticed.
Hi Susan, I know you have made a wooden drum, but have you looked at the "stumpy nubs" sander. He used a heavy duty PVC pipe for his and even made his so that you could have lots of different grits of sandpaper. it might be the perfect answer to your problems.
.1 mm? It seems like the sandpaper itself would introduce more variance than that.
MDF would be more stable than plywood. Are you still using this machine?
id look at the frame, plywood is pretty stable
By 'we' do you mean us? Minor point but I think this is your problem. There is a Canadian company that provide a great drum setup...... When I made mine the velcro fitting of paper was great and the whole kit was stable and my workshop had great fluctuations...
Good to be true.
I don't know if you still read your comments at this late date. But I had attempted to make a drum sander with not such good results. I ran into your video's and thought, it is a better design than what I had tried. I'm also glad for this "final video" and all of the others so I can avoid the problems you ran into. Your video's are informative and entertaining. What a treat! Thank you.
Thank you. I hope you have success with your sander :-)
Success! Did some sides for a upcoming guitar within a 10th of a mil. Thanks for all your work on the videos!