Proscale/Accurate Technologies DRO on Supermax 19-38

[Gabriel Marusic]

Is anyone out there by chance using one of these DROs on their Supermax? I’m trying to install mine and can’t seem to figure out if and how I can install it with the supplied brackets. Hoping I don’t need to drill into the sander or fab up a custom bracket to make it work. The only examples I’m seeing online are for the wixey which has a bracket setup specific for this machine which mine does not.

[Bill Dufour]

Do you really care about accuracy or is repeatably all that matters? For most repeatability is more important.
That said, if all you need is repeatability, accuracy in mounting it exactly parallel or normal to machine travel becomes much less important. Do not over think it. It could be off by 45 degrees and still be very useful.
A good dro will have an adjustment factor that can be programed in to compensate for poor mounting.
Bill D

On a metal working lathe the top slide measurement is usually set off by 30 degrees. The sine of 30 degrees is 1/2 so the math is almost automatic.

[Zachary Hoyt]

I don't think a DRO will help much on a drum sander. If I leave the crank in the same place and keep running wood through it will take off a couple of thousandths or so each time for the first few passes. I don't know why, maybe the sandpaper is pulling very slightly way from the drum or something.

[Bill Dufour]

Probably springback on the metal bits. You need to take a spring pass at the end.
Bill D

[roger wiegand]

I have a DRO on my sander and have found it to be completely useless. Too many other variables and too much flexibility in the paper and supporting belt for the precision of a DRO. The fixed indicator scale has plenty of accuracy given the variability within the machine. You can't set the DRO to a value and expect the wood to come out that thick; it won't happen. Too many springy parts.

[glenn bradley]

This is good info for me. was in the middle of fabricating a way to put the DRO on my 19-38 that used to be on my router table. I found I never used it on the RT and thought is might be nice on the 19-38. I just sort of lost interest in fabricating the bracket. Maybe the shop gods were telling me to put the DRO in a drawer and wait for a more useful place for it.

[Jim Becker]

While I don't depend upon the DRO on my 19-38 for "thickness accuracy", I do find it useful as a visual aid for setting up and running material. Since it's dual scale (metric and inch) it's got the flexibility I need for how I use it. I do agree that the nature of the drum sander is what makes the DRO "less useful" for thickness accuracy as compared to a thickness planer for sure.

[Mark Bolton]

The key to the DRO on any sander is the procedure up to the point the work goes into the sander. No different than any tool really but more critical with a sander due to rubber/cushioned drive belts on some, and on lighter machines machine flexure. DRO on the sander for us is critical but we also come off the planer with a DRO so the material that comes out of the planer is a specific dimension and then goes through the sander with a specific number of set passes (or single pass) to an exact final dimension. Like mentioned in another response, if you feed two boards of slightly different thickness through the sander without changing anything on the sander, you will get two different dimensions out. Same thing happens with most anything other than massive planers. You hog off a monster pass or a lighter pass and without changing anything machine flexure, your parts will vary in final dimension.

The key to the DRO on the sander is to come off the planer at a dead fixed dimension leaving exactly what the sander will take off leaving you at a dead repeatable final dimension. No matter what we are doing we come out of the planer leaving .0125 per face for the sander. So if we want .812 final dimension with both faces sanded, we plane to .837. First pass through the sander is at .8245, second pass is at .812 and its perfect every time dead repeatable. The increase in speed and being able to go back an run an extra part 3 days later that is exact is well worth it.

But its completely correct. You send the .812 through again (spring pass) and it will take more, a third time, more, fourth more, because there is enough slop/play/cushion in the machine that it will never "spark out" like a surface grinder.

Put DRO on your planer and sander and setup a routine (write it on the top of the machines with a sharpie) and you'll never regret it. Small sanders are painfully slow anyway so getting it to a point of a single pass or two is well worth the work.

[Ron Selzer]

The key to the DRO on any sander is the procedure up to the point the work goes into the sander. No different than any tool really but more critical with a sander due to rubber/cushioned drive belts on some, and on lighter machines machine flexure. DRO on the sander for us is critical but we also come off the planer with a DRO so the material that comes out of the planer is a specific dimension and then goes through the sander with a specific number of set passes (or single pass) to an exact final dimension. Like mentioned in another response, if you feed two boards of slightly different thickness through the sander without changing anything on the sander, you will get two different dimensions out. Same thing happens with most anything other than massive planers. You hog off a monster pass or a lighter pass and without changing anything machine flexure, your parts will vary in final dimension.

The key to the DRO on the sander is to come off the planer at a dead fixed dimension leaving exactly what the sander will take off leaving you at a dead repeatable final dimension. No matter what we are doing we come out of the planer leaving .0125 per face for the sander. So if we want .812 final dimension with both faces sanded, we plane to .837. First pass through the sander is at .8245, second pass is at .812 and its perfect every time dead repeatable. The increase in speed and being able to go back an run an extra part 3 days later that is exact is well worth it.

But its completely correct. You send the .812 through again (spring pass) and it will take more, a third time, more, fourth more, because there is enough slop/play/cushion in the machine that it will never "spark out" like a surface grinder.

Put DRO on your planer and sander and setup a routine (write it on the top of the machines with a sharpie) and you'll never regret it. Small sanders are painfully slow anyway so getting it to a point of a single pass or two is well worth the work.

Thank you for this explanation, helps to understand this process better
Ron

[glenn bradley]

The key to the DRO on any sander is the procedure up to the point the work goes into the sander. No different than any tool really but more critical with a sander due to rubber/cushioned drive belts on some, and on lighter machines machine flexure. DRO on the sander for us is critical but we also come off the planer with a DRO so the material that comes out of the planer is a specific dimension and then goes through the sander with a specific number of set passes (or single pass) to an exact final dimension. Like mentioned in another response, if you feed two boards of slightly different thickness through the sander without changing anything on the sander, you will get two different dimensions out. Same thing happens with most anything other than massive planers. You hog off a monster pass or a lighter pass and without changing anything machine flexure, your parts will vary in final dimension.

The key to the DRO on the sander is to come off the planer at a dead fixed dimension leaving exactly what the sander will take off leaving you at a dead repeatable final dimension. No matter what we are doing we come out of the planer leaving .0125 per face for the sander. So if we want .812 final dimension with both faces sanded, we plane to .837. First pass through the sander is at .8245, second pass is at .812 and its perfect every time dead repeatable. The increase in speed and being able to go back an run an extra part 3 days later that is exact is well worth it.

But its completely correct. You send the .812 through again (spring pass) and it will take more, a third time, more, fourth more, because there is enough slop/play/cushion in the machine that it will never "spark out" like a surface grinder.

Put DRO on your planer and sander and setup a routine (write it on the top of the machines with a sharpie) and you'll never regret it. Small sanders are painfully slow anyway so getting it to a point of a single pass or two is well worth the work.

This is interesting info. What kind of make/model sander are we talking about? Maybe the DRO on the sander isn't such a bad idea after all and I should finish up? I have them on my planer and my tablesaw and would not give those up easily.

[Mark Bolton]

It doesnt matter what the sander is. You simply have to qualify at what thickness of material removal your sander removes at a given amount of material per pass. If you plane to .900 and send it through a 3 head widebelt with a platen removing XXX amount of material... every time you repeat that exact process you should be extremely close in your end result. Finding your ultimate heavy sanding pass may be fine for some but I want my abrasive to see the lightest (coolest) amount of work necessary so Ive landed on .012" per pass being the very lightest I can take and cleanup the planer marks and leave me the minimal amount of RO work. Its just finding whatever the sweetspot is for the work you do. But regardless no one with a 3 head machine is interested in burning up abrasives when that material can land as chips off the planer in the DC. You get rid of all of it you can and take the minimum needed through the sander regardless of its size (maybe unless your abrasive planing).

Smaller sanders, open ended, maybe you have to plan for 2 pass per face so you can flip and knock down some of the cantilever flexure, who knows. The bottom line is, to Bill's point, even machinists break up material removal into even amounts of stock removal because of machine flexure/tool pressure. You have .200 to come off, break it into 3 passes at .066 a pass. Its the same principal. If for whatever reason your going to need extra material for the sander, fussy material, bad tearout, leave 2-3 more passes on the rough stock but stick with your fixed material removal (in my case .0125) and whether its 1, 3, or 5 passes,... with the DRO you'll land there pretty damn close.

Paper going away, if your drum is hook and loop, hard/soft material, may play a bit but its worked for me. I wouldnt be with out the DRO on a sander. Too much fishing around and multiple passes. When your talking a small sander your talking passes that are un-readable on a scale. Your reading handle cranks and thats a waste of time.

[Gabriel Marusic]

Do you really care about accuracy or is repeatably all that matters? For most repeatability is more important.
That said, if all you need is repeatability, accuracy in mounting it exactly parallel or normal to machine travel becomes much less important. Do not over think it. It could be off by 45 degrees and still be very useful.
A good dro will have an adjustment factor that can be programed in to compensate for poor mounting.
Bill D

On a metal working lathe the top slide measurement is usually set off by 30 degrees. The sine of 30 degrees is 1/2 so the math is almost automatic.

It's definitely for repeatability. I don't always work in a linear fashion and being able to go back to a previous setting and count on it is huge for me.

[Gabriel Marusic]

While I don't depend upon the DRO on my 19-38 for "thickness accuracy", I do find it useful as a visual aid for setting up and running material. Since it's dual scale (metric and inch) it's got the flexibility I need for how I use it. I do agree that the nature of the drum sander is what makes the DRO "less useful" for thickness accuracy as compared to a thickness planer for sure.

Yeah, I'm not expecting to dial it into thousandths of an inch type deal for final thickness but do want it for repeatability and being able to setup my starting points better.

[Jim Becker]

Yeah, I'm not expecting to dial it into thousandths of an inch type deal for final thickness but do want it for repeatability and being able to setup my starting points better.

I think that on these machines "repeatability" is relative, considering that the up/down movement is a little coarse for really high levels of accuracy. But for "reasonable" thickness repeatability, you likely will be fine, especially if you do that extra pass without resetting at the end of the job.

[Alan Lightstone]

I think that on these machines "repeatability" is relative, considering that the up/down movement is a little coarse for really high levels of accuracy. But for "reasonable" thickness repeatability, you likely will be fine, especially if you do that extra pass without resetting at the end of the job.

+1. I was very happy that I had installed a DRO on my Jet 16/32. Yes, I checked the thickness of the pieces with a separate DRO on a workbench when getting close to final dimensions, but the DRO enabled me to get very close to perfect while not overshooting my target thickness. And that extra pass without resetting does help with repeatability. IMHO.

And having the DRO on the planer is also incredibly useful. I love the system built into my Felder planer. Bang on accurate. I use that to get close to final thickness, and leave enough room for my wide belt sander to finish the job. Certainly not an original workflow, but it works every time.

I'm a huge believer in DROs. I have them on my planer, tablesaw, router table (both fence and bit height), and am working on finding ways to use them on my bandsaw (boy I'd love that), and even my panel saw and miter saw (those last two are crazy expensive). But I'm a digital geek, so there's that...