Almost embarrassed to ask - ROS sander and abrasive question....

[Clark Harbaugh]

My 15 year old PC sander has bit the dust (mid project, mind you), so now I'm shopping for a new sander. I've run the searches on here and see that the Festool are overwhelmingly recommended. I'm just not sure if budget allows for it at the moment. I also see several people speaking highly of the Bosch ROS65VC, which is within budget. My application is mostly finish sanding after assembly, typically 120 grit and up. The embarrassing part is that I've never really given much though to what I've used for sanding. I've just bought the 8 hole sanding disks at the local borg store and gone about my merry way with my PC sander. I can tell you a couple thing I've always detested about the sanding process - 1) my hands vibrate for hours after I'm finished, and I hate that; 2) I typically hook up my sander to my plumbed dust collection, which at best has only been moderately successful (not to mention the cumbersome hose....); and 3) I go through sandpaper like it's toilet paper. I've just never looked at what different abrasive options are.

So, I guess my questions for the group are -
- if using the Bosch (or any other non-Festool), is there a brand/type of sandpaper that is better than what I've been using that will last longer and be worth what I'm expecting to be more $$ (I'm anticipating that to be an overwhelming 'yes')?
- While I would love the Festool system with dust collection, if I were to go with a Festool is there any reason not to use it with my regular dust collection system? I'm pretty sure the answer is no, but wanted to check.

I'm really trying to come to a justification of the Festool, but the cost of the sander and outfitting all of the sandpaper is way more than I'd like to spend on an unexpected replacement.

[Jim Becker]

I originally used a pair of PC sanders. They left my hands numb in a very short period of time. That is the primary reason I bought my Festool 150/3...and the excellent dust collection was a bonus. I can literally sand for hours without any numbness or pain. The moral to this story is that if this is a tool you're going to use frequently, want it to be comfortable and effective, and you want it to last, buy Festool, higher end Bosch, Mirka, etc.

For dust extraction, your big DC isn't the right tool. Dust collectors operate by moving large amounts of air at low (negative) pressure which in turn, moves the dust and chips. That can't happen through a small hose. Vac based extractors operate at high (negative) pressure and will function well through a smaller hose. You do not need to buy a Festool extractor to use with their sanders. You'll want the hose or at least a proper hose adapter, but you can use any vacuum for them, from an el-cheapo generic shop vac to something better and quieter. You'll want a means to reduce the vacuum as you move up through the abrastives to finer and finer to avoid "sticking" the tool to the workpiece. That can be done passively with a bleeder on the hose or with a "dial it down" feature on better vacuums. These things apply to any ROS, BTW.

[Bill Dufour]

Any sandpaper made in China is garbage. A quality paper will outlast it by five to one or better. I like Mirka brand made in Finland. Old computer floppy disk cases hold the 5" disks nicely. Folks wear the gel bicycle gloves to reduce vibration.
Bill D

[Myles Moran]

I've got the Bosch ros65vc, and when I bought it I also made the jump to the mirka abranet system. It amazes me how little dust is produced now, even without running the shopvac on it. Before I used the mirka gold discs, but I'd go through so many, especially with how fast they loaded up and I couldn't get them clean. With the abranet discs, I'll use one basically until I catch an edge and rip it. I recently did a king size bed and got through the whole project with just one disc of each grit.

I also considered the festool, and while everyone who has one loves it, I couldn't justify it for the price jump over the Bosch.

[Clark Harbaugh]

Thanks for the info. Great, so now I'm not only buying a sander, but also some sort of dust extraction....:)

[Mike Henderson]

Thanks for the info. Great, so now I'm not only buying a sander, but also some sort of dust extraction....:)

A regular wet-n-dry vac will work for dust collection on your sander. There are some low cost things you can add to a vac to have it turn on when you turn on your sander, and to slow it down if the suction if to much. If you decide to go that way I can tell you more about those extras.

Mike

[Jim Dwight]

It is a different sort of sander but I have and recommend the Bosch DEVS 1250. It has a turbo mode that is very aggressive but it also has a normal random orbit mode. That is also faster than many due to the 5mm orbit. Dust collection is pretty good using my Rigid shop vac pulling through a dust deputy and a Bosch 5 meter hose. I use the same vacuum and hose with my Festool Domino and DeWalt track saw. I also have an auto on switch on the shop vac. My setup is not nearly as nice as a Festool dust extractor but it does the same job.

[Tom M King]

I'll second what Jim said about the 1250. I call Turbo mode: Beast Mode. It beast mode it's about as aggressive as a belt sander, but in regular mode is a really nice finish sander. Mirka Abranet mesh disks, and a big Shop Vac with yellow Hepa bag leaves little to be desired in a ROS.

[Matt Day]

That Bosch is basically a Festool Rotex, at half the price. I have an RO90 which is good for small stuff, but I’ll be buying a Bosch for hogging bigger stuff to compliment my ETS EC 125.

I’d suggest the Bosch as a do all sander. And since your paper sucks, might as well start buying good 6” paper.

[jerry cousins]

just a little side-step on this discussion -
mike - what are the add-ons for a shop vac as a dust collector?
thanks, jerry

[Ron Selzer]

look at 2sand.com for choices of sanding media, Klingspor is another one, lots and lots of choices out there
use a dust deputy or a CV06 Mini Systemwhich is what I use and really like

[Mike Henderson]

just a little side-step on this discussion -
mike - what are the add-ons for a shop vac as a dust collector?
thanks, jerry

To control the speed you use one of those "router speed controls (https://www.amazon.com/Newest-Variable-Controller-Electric-Rheostat/dp/B07PYGCHXY/ref=sr_1_8?crid=3KFIQOG8DCXV&dchild=1&keywords=router+speed+controller&qid=1589943761&sprefix=router+speed%2Caps%2C209&sr=8-8)". They're available on Amazon and many other places. To start the vac when you turn on your sander, the automated vacuum switch (https://www.amazon.com/iVAC-10031-010-Automated-Vacuum-Switch/dp/B0035YGLZG/ref=sr_1_6?crid=27FILWF2VBZD1&dchild=1&keywords=i-vac&qid=1589943675&sprefix=i-vac%2Caps%2C209&sr=8-6) is a good solution. There's a cheaper version but this one allows you to turn the vac on with a switch which is nice when you want to use it to clean up some stuff.

Add a HEPA bag to your vac and you have the equivalent of a Festool vacuum at a much lower price.

Mike

[The router speed control is designed to work with universal motors, which is what is in a shop vac.]

[Mark Gibney]

Regarding what sandpaper to use - I got all the grits of the blue Festool 6" sandpapers when I got the vacuum and the Festool RO sander.
I've since switched over to Klingspor, which seems to me to be just as good.
It was convenient for me to do so, I get my regular sandpaper from Klingspor and so I just added on the 6" discs.

One odd thing about the Festool discs is that the 240 grit seemed to wear out strangely quickly, even the 320 would have life in it for long after the 240 was just polishing. I'm guessing I just happened to get a rouge lot.

[Rod Sheridan]

I use a Festool125 sander, as Jim said my hands don't go numb when using it.

It has great dust collection, Mike has given you some tips on how to use a modified shop vacuum, I can't be bothered and simply bought the Festool Midi vacuum, light, quiet, compact. Wound up buying a second one for the house because Diann liked it so much.

I use the Mirka Abranet paper, works great...........Regrds, Rod.

[Orlyn Gaddis]

Another ROS sander you might consider besides the Festool, Bosch, and Mirka previously mentioned is the electric AirVantage ROS (also comes as a pneumatic version). It comes as both a fully self-contained sander as well as a version with a separate power source (similar to the discontinued Mirka Ceros). It is a less expensive alternative to the Festool and you may find it more reliable as well. I also use the Mirka Abranet sanding discs on both my Airvantage Standard series ROS (the one with the separate power supply) and my Festool ETS EC 150/5 and the discs work equally well on both sanders and last much longer than more conventional sanding discs. Dust collection is outstanding with these discs and I just use a Rigid shop vac from Home Depot with the addition of a cyclone separator. Both of these sanders are great at virtually eliminating vibration.

[Jim Becker]

To control the speed you use one of those "router speed controls (https://www.amazon.com/Newest-Variable-Controller-Electric-Rheostat/dp/B07PYGCHXY/ref=sr_1_8?crid=3KFIQOG8DCXV&dchild=1&keywords=router+speed+controller&qid=1589943761&sprefix=router+speed%2Caps%2C209&sr=8-8)". They're available on Amazon and many other places.

May be safer to use a bleeder on the hose...many vac, especially inexpensive ones, rely on the air flow from the hose for cooling. Slowing the motor slows the air flow. With a bleeder, you reduce "suction" at the tool but still have full air flow through the vac.

[Mike Henderson]

May be safer to use a bleeder on the hose...many vac, especially inexpensive ones, rely on the air flow from the hose for cooling. Slowing the motor slows the air flow. With a bleeder, you reduce "suction" at the tool but still have full air flow through the vac.

Several people have pointed to this objection in the past. The reason it's not a problem is that the electrical power required to drive a fan (which a vacuum is) varies with the third power of the RPM. So when you slow down a fan (vacuum) you greatly reduce the current flowing through the motor and the heat generated.

And for a real world experience, I've used a "router speed control" on my shop vac for years connected to my sanders. Never a hint of a problem.

Mike

[Someone should check me but I think the equation is W2=W1(RPM2/RPM1)^3 Where W=Watts. I'm going from memory here. Can also be written as W1/W2=(RPM1/RPM2)^3]

[Andy D Jones]

Several people have pointed to this objection in the past. The reason it's not a problem is that the electrical power required to drive a fan (which a vacuum is) varies with the third power of the RPM. So when you slow down a fan (vacuum) you greatly reduce the current flowing through the motor and the heat generated.

And for a real world experience, I've used a "router speed control" on my shop vac for years connected to my sanders. Never a hint of a problem.

Mike

[Someone should check me but I think the equation is W2=W1(RPM2/RPM1)^3 Where W=Watts. I'm going from memory here. Can also be written as W1/W2=(RPM1/RPM2)^3]

The complete question is not whether the power dissipation reduces, but does the power dissipation reduce as fast or faster than the cooling system's reduced ability to remove waste heat from the motor.

The above equation should not be extrapolated to indicate that anything that causes RPM to go up, also increases power dissipation, or vice versa.

-- Andy - Arlington TX

[Mark Hockenberg]

Hi Clark,

I'm a little late to the tread, but wanted offer my two cents worth. I went from my old PC RO sander to a Festool ETS EC 125 and a Festool dust extractor. Although pricey, it was more than a game changer, it was a life changer. Sanding went from something I dreaded to something I almost enjoy now.

Cheers,
Mark

[Mike Henderson]

The complete question is not whether the power dissipation reduces, but does the power dissipation reduce as fast or faster than the cooling system's reduced ability to remove waste heat from the motor.

The above equation should not be extrapolated to indicate that anything that causes RPM to go up, also increases power dissipation, or vice versa.

-- Andy - Arlington TX

I suppose we could have a fan system where the motor is only cooled adequately by it's internal fan at the standard operating RPM, and when you slow it down it begins to overheat because the fan doesn't cool it adequately. But that would be counter to experience with fans that have speed controls built into them.

From actual experience I can say that years of use of a shop vac at reduced RPM has not caused any noticeable harm to the unit. Given that the input power is reduced by the third power of the reduction in RPMs I'd highly doubt if the heat generated could outrace the fan cooling.

Can you point to a fan system that will overheat when it is slowed down?

Mike

[I would expect the opposite to be true: When you overspeed a fan the motor may get excessively hot because the input power is increasing with the third power of the RPMs.]

Let me run some numbers. Let's take a shop vac operating at 120 volts and 10 amps. Ignoring power factor the input power is 1,200 watts. Universal motors are not very efficient - let's assume 50% efficiency. Using that the watts going to heat is 600 watts per second. When you turn the vac on, the motor will begin heating until it reaches a temperature that allows 600 Watts per second to be conducted to the airflow around the motor. At that point, the temperature of the motor will stabilize.

Now, let's slow the motor down by 50%. The third power of 0.5 is 0.125 so the input power to the motor will be 150 watts. If the efficiency remains the same, the watts of heat will be 75 watts per second. The motor will stabilize at a temperature that allows those 75 watts per second to be conducted to the new airflow.

To show that the motor will overheat in this situation you need to show that the 75 watts per second cannot be conducted into the airflow unless the motor becomes excessively hot.

I would expect the motor to run cooler under half speed.

Now let's look at overspeeding. If the RPMS are raised by 20%, the factor is 1.2 which raised to the third power is 1.728. So the input power would have to be 2,073 Watts. If the efficiency remains at 50%, the heat is now 1,037 (rounded) watts per second. A very significant increase for only a 20% increase in RPMs.]

[Brian W Evans]

I have two Bosch sanders with vibration control that replaced an old PC ROS. The difference is night and day regarding the comfort and lack of numbness. I'm very pleased with dust control, for which I use a Fein Turbo II with a dust deputy. The hose on the Fein has a bleeder built in and the vac has an outlet for auto-on and off when the sander is turned on and off. I'm not sure how much better this setup could be, but I've never used a festool sander, so...

[Andy D Jones]

Mike,

I'm not saying that it will overheat, but I am saying that neither you nor I know that it won't overheat for an arbitrary shop vac and application.

I have no experience with operating shop vacs with after-market PWM variable speed controls. I do have 34 years of electrical engineering experience to understand whether all potential impacts of a design change are adequately addressed.

I would not use one of the typical aftermarket PWM variable speed controls for universal motors, but I know many people have used them without issue, particularly for routers (not necessarily shop vacs). I do not know how much they stressed their equipment otherwise.

I also know that, to the extent that slower cooling airflow becomes less turbulent over the motor, heat transfer from the motor to the cooling air will be reduced significantly (beyond proportionately to airflow). How much? I don't know; that's why I'm suggesting caution.

-- Andy - Arlington TX

[Mike Henderson]

Mike,

I'm not saying that it will overheat, but I am saying that neither you nor I know that it won't overheat for an arbitrary shop vac and application.

I have no experience with operating shop vacs with after-market PWM variable speed controls. I do have 34 years of electrical engineering experience to understand whether all potential impacts of a design change are adequately addressed.

I would not use one of the typical aftermarket PWM variable speed controls for universal motors, but I know many people have used them without issue, particularly for routers (not necessarily shop vacs). I do not know how much they stressed their equipment otherwise.

I also know that, to the extent that slower cooling airflow becomes less turbulent over the motor, heat transfer from the motor to the cooling air will be reduced significantly (beyond proportionately to airflow). How much? I don't know; that's why I'm suggesting caution.

-- Andy - Arlington TX

I understand your concerns. It's impossible to calculate the heat flow for a shop vac because we don't know all the parameters required to do the calculations. But sometimes you just have to make a decision based on imperfect information.

The thing that gives me confidence is the third power factor. As an electrical engineer, you know how quickly a factor changes when it's raised to a power, and the third power is more than we usually see. A factor raised to a third power changes significantly.

When we can't calculate all of the parameters we usually fall back on experimentation. Of course, my use of a shop vac under the conditions described is an experiment but more importantly, thousands of people have used those "router speed controls" on universal motors successfully for many, many years. If universal motors were failing when those controls were used on them we'd be getting lots of reports because failures get reported more readily than successes.

I have no problems recommending the use of a "router speed control" for slowing down a shop vac.

Mike (also an electrical engineer with a lot of years in the business - since 1968)(But credentials don't matter. What matters is making sense.)

[Also, I'm pretty sure that Festool and Fein use this system to control the speed of their vacuums. I'm pretty sure they use a universal motor in their vacuums and there are not many low cost ways of doing speed control other than pulse width modulation. In fact the speed controls built into things with universal motors (like routers) are probably PWM devices.]

[Andy D Jones]

Mike,

It's not the PWM that worries me, it's whether the vendor has considered and accounted for the effects of PWM within their system, let alone whether the motor is sufficiently cooled across the manufacturer's defined range of speeds. Some 3rd party controllers allow you to vary the speed all the way down to zero. Wonder why EVS tool vendors don't do that in most cases?

And it's not just universal motors with PWM voltage control...

Even using VFDs on 3-phase motors (PWM is used to generate the variable frequency phases), without sufficient filtering, can cause motor bearing damage. The filtering need not reduce or remove the high frequency PWM power content, but it should induce such currents to return through the power wiring, instead of to ground via the structure and bearings. A simple common mode choke can do exactly that. Good VFD vendors recommend and supply such filtering. Luckily these filters are not expensive, but they are not free either, so the cheap vendors won't bother telling you that you need it, especially if they don't provide it. Without such filtering, running a VFD on a GFCI circuit can can trip the GFCI. Many VFD suppliers recommend not using them on GFCI circuits.

PWM is not inherently bad, but it does cause some unusual issues that have to be dealt with at the system level for reliable operation.

-- Andy - Arlington TX

[Mike Henderson]

Mike,

It's not the PWM that worries me, it's whether the vendor has considered and accounted for the effects of PWM within their system, let alone whether the motor is sufficiently cooled across the manufacturer's defined range of speeds. Some 3rd party controllers allow you to vary the speed all the way down to zero. Wonder why EVS tool vendors don't do that in most cases?

And it's not just universal motors with PWM voltage control...

Even using VFDs on 3-phase motors (PWM is used to generate the variable frequency phases), without sufficient filtering, can cause motor bearing damage. The filtering need not reduce or remove the high frequency PWM power content, but it should induce such currents to return through the power wiring, instead of to ground via the structure and bearings. A simple common mode choke can do exactly that. Good VFD vendors recommend and supply such filtering. Luckily these filters are not expensive, but they are not free either, so the cheap vendors won't bother telling you that you need it, especially if they don't provide it. Without such filtering, running a VFD on a GFCI circuit can can trip the GFCI. Many VFD suppliers recommend not using them on GFCI circuits.

PWM is not inherently bad, but it does cause some unusual issues that have to be dealt with at the system level for reliable operation.

-- Andy - Arlington TX

Well, I suppose if you put your mind to it you can find a hundred problems and reasons why something won't work - some people make a career out of doing that.

However, we have thousands of users who use those "router speed controls" successfully - they don't know of all those possible problems so they just move forward and do. While the points you made may be true, they don't appear to be serious enough - or common enough - to cause problems in the real world.

Mike

[jerry cousins]

wow - i guess it was a big side step
but interesting
jerry

[Tom M King]

I just hook mine up, and use it.

[Scottie Findley]

i have the Bosch Dual Mode sander coupled with the Mirca Abranet, I've been blown away at the quality of it and the lack of dust when used with my lousy vacmaster shopvac. The sander is heavy and will dive you a good workout in the turbo mode, however on the regular ROS I let it sit on the surface and guide it around the workpiece with two fingers on the hose port. When I want something lighter and quieter (it's quite loud), I use my battery powered Dewalt ROS. It's very light and I'm quite happy with the combination of sanders. My 5 year old daughter likes to help sand and has no problem using that one. That being said the smaller one is also easier to use when having to sand narrow objects or the side of things.

Last night my daughter and I sanded a rough end grain cutting board, I started with the Mirca 80 grit discs and worked my way up to 120 grit before switching to ROS mode, we continued up to 400 grit and produced the smoothest cutting board I've ever felt (end grain or not). The sanding for both sides and edges of the 12x16x2 cutting board took about 40 minutes, that includes about 10 minutes of my daughter working with the Dewalt. All in all I'd recommend having two sanders, the Bosch dual mode and a quality battery powered ROS (having no cords while doing detail and edge sanding is a huge plus!

[Stan Calow]

When I use my Bosch inside, I hook it up to a small shop vac with the 1 1/2" hose. My adapter is usually duct tape. Rockler sells a universal adapter. I got the small (1.5 gallon) shop vac at a garage sale for a few bucks, and only use it for the sander.

[Pete Staehling]

I sand mostly smaller work pieces and swap grits frequently so I have several sanders set up with different grits. I know it is quick to swap disks, but i have three sanders with progressively finer grits and find it pretty handy when working on small pieces where I'd be swapping grits constantly. I find my DeWalt sanders to be not too bad vibration wise and they have held up well. I have used others that were terrible on my arthritic wrists or didn't hold up as well.

I don't usually bother to hook them up to the DC. The little bag catches a lot of the dust and I most often sand on the out feed table of the thickness sander (remember that I am working with smaller work pieces) with the DC turned on for the thickness sander it sucks up the air born dust pretty well.

Really cheap abrasives are a waste of money, but there can be decent stuff at prices that aren't terrible. In general I buy a lot of abrasives from Klingspor, but I have currently only Mirka in stock for the ROS because I stocked up with a large purchase when they were on sale.

[Jim Andrew]

The Bosch Ros 65vc I have is an awesome sander. The VC stands for vibration control, and the 65 means it can be 6" or 5". It can easily be used with one hand, and has a dial speed control. I use mine with a 1 1/4" inch hose on a Cman shop vac, also have their automatic switch, you plug the switch into the receptacle and plug your vac and your tool into the box, makes the vac automatic.