The weather was very nice so I disassembled the drum sander, took it outside, and slathered blue paint all avo. I painted all exposed particle board surfaces because I want to make sure it does not swell and crumble if I accidentally spill a few drops of water on int in my workshop. I did not do a very neat job but from a distance, it does not look so bad.
© Charly, all rights reserved. Click for full size.
I did not paint the tilting table because the paint there would be a hindrance and not a boon.
I also improved the inner geometry of the dust cover by gluing in two pieces of polystyrene and grinding them on the drum until there was just a small gap.
© Charly, all rights reserved. Click for full size.
The P40 abrasive with velcro finally arrived and it is scary stuff.
© Charly, all rights reserved. Click for full size.
Just putting it on mangled my fingers so much I had trouble logging into my phone via fingerprint recognition for a few days. I forgot to put in the safety screw on the right side as you can see in the picture. It did not appear to be a big deal, just folding the paper into the cut was enough and it run without a hitch for a few hours before I noticed the missing screw.
I was baffled at first that even with 40 grit it took me two hours to flatten four boards, i.e. with the same speed as with 80 grit. The machine was stalling all the time whenever I tried to be a bit more aggressive with it. And after two hours I realized that the leather belt stretched a bit and did not have enough tension to power the drum effectively. I knew that the belt would stretch with time so it is a tad embarrassing that it took me two hours to realize it had done so already. After I corrected the tension (by making a jig for precise cutting of the belt at an angle and shortening it), I breezed through the remaining six boards in about an hour and a half, i.e. twice as fast.
After that, I cut these boards into strips with my table saw.
© Charly, all rights reserved. Click for full size.
I took some of these and I glued an end-grain cutting board of the biggest size I intend to make – ca 30×50 cm – and I am currently in the process of flattening it.
© Charly, all rights reserved. Click for full size.
This one will not be for sale since it is a learning piece. I will use it personally to see how it performs but it has some gaps and thus it will probably serve mostly as a pretty background for photographing knives.
I learned that I will have to take more time and care with the glue-up to save time when flattening the glued piece. Jatoba is extremely hard in all directions but trying to sand or plane the endgrain is truly a penance. I spent three hours today doing it and I am nowhere near finished. At least that is an assurance that if I make and sell cutting boards from this wood, they will last.
When I figure out the ins and outs of making the cutting boards I will post about it. As far as the drum sander goes, it is finished and functional. All that remains is to figure out where to store it when it is not in use
At $WORK we used to have a Wadkin JTA disc/bobbin sander in the model shop. The 760 mm disc was usually covered with 40 grit abrasive, bonded with hide glue. With the disc spinning at 900 rpm, you could see whatever you pushed against the outer edge getting shorter! I learned very quickly to keep my fingers well away.
It seems that your table saw does not like Jatoba too much. Is the blade dull?
Jatoba is extremely hard, I just looked up the numbers on Google and it is twice as hard as oak. It is virtually impossible to cut it on the table saw without burning it. When using a belt sander, I must reduce the speed and work slowly, especially when working on the end grain. Working it by hand is not recommended.
I checked every tooth on the saw and they seemed sharp. I cannot sharpen them myself (carbide tipped) and it really looks like the problem is the hardwood that I work with, not the saw blade itself. Cutting pine or particle boards is OK. Maybe the tooth geometry/spacing is not correct for wood this hard. But I do not know enough about table saws to get a better-suited saw blade and they are expensive enough for me not to want to experiment.
When you’re sawing Jatoba, do you get real chips or is it more like dust?
If you get dust and burns, it can help to increase the feed per tooth. This can be done by feeding faster if the saw has enough power and there is enough space between the teeth to clear the chips.
If the saw gets bogged down when you push harder, try making the the cut in two passes. Or you can keep the feed speed the same but reduce the speed of the saw if that is possible on your table saw.
Thank you for the info. I do not know if I interpreted it correctly, but today I had an opportunity to go to Obi (our equivalent of Home Depot) and I bought a new blade with fewer teeth (just 24, the old one had 40). And it breezed through a jatoba board like a hot knife through butter with no discoloration.
When I had the old one out, I cleaned it as best as I could from all the burned-on crud and cleaned all teeth with a diamond-coated tool in Dremel. It is not exactly sharpened now but it is in a better shape than before which is a definitive plus. I tried it on Jatoba too and the burning was about 20% of what it was before and I also could cut much faster.
I will keep it for cutting material of questionable origin -- with a close and detailed inspection, I found a few slightly chipped teeth. Now that I think about it, I remember hitting a stone when cutting a rootball two years ago. I do not use the saw that often for the slight bluntness to be a massive issue but now when I want to make cutting boards I do need a really sharp blade for precise cuts. The new blade is also slightly thicker thus it flexes less and cuts more precisely.
Glad that the new saw worked! Good tools are half the job.
At $WORK we generally send out blunt saws for sharpening. Probably not an option for a private person unless Obi has a sharpening service. Hornbach and other sell the “Holzmann MTY8-70” saw sharping machine, but at around €270 it’s not exactly cheap.
It you are interested, there are several videos online about how to make a decent sharpening jig for saw blades. Since you need to touch up both the front and the tops of the teeth for proper sharpening, a jig helps a lot to get consistent teeth.
One thing to watch out for when sharpening cemented carbide tooling is the dust generated by the process. The generated particles can irritate the skin and mucus membranes. They’re also toxic because of the heavy metals like cobalt and nickel used as binders in cemented carbide tooling. So using a shopvac and wearing a dust filter mask is a good idea.
There was a shop nearby that offered sharpening service but he retired two years ago and for a 40 tooth 254 mm blade, it would be cheaper to buy a new one anyway.
The Holzman MTY8-70 is really not worth it for me unless I intend to make a business from sharpening saws, which I don’t, there is not a big enough market for it. However, now that I have looked into it, I see there is a cheap sharpening machine on the market for these smaller blades that costs about as much as three new blades (Güde GSS 400, just about 60 €). It is compact enough to fit into my workshop and to be stowed away when not in use. It might be worth buying in the future if it manages to sharpen a blade at least four to five times before it has to be tossed. I will read some reviews when I have time.
For now, it is not worth my time and effort to faff around with sharpening saw blades but thanks again for the feedback, it helped.