wanted,motor replacement for Micro Mark 83507 drum thickness sander.

[reklein]

Anybody know where I could order a motor from? Not getting any response from MM after a phone call and an e-mail to customer service. Its a 12 V. 1/8th hp 4000rpm motor.      

 

 

Bill

[Jaager]

The advertising copy has the motor as 1/3 HP AC and drum speed 5800 rpm.

 

MM re-brands a manufacturer product, often from China or Taiwan,  so sometimes it is possible to skip the middleman and source a new motor from the mfg - who is a middleman for the actual motor mfg.

 

The design as it appears looks to offer some options, if you are willing to do custom mounting of a new motor.

The diameter of the pulleys can affect the ultimate drum rpm.

The enclosed and vented box for the motor is a bad design for motor life.  More air flow - more surface area - means a cooler running motor.  Hot motor = decaying motor.

 

I have been thinking that the sweet spot for sanding is a 1700 rpm motor.  Too fast a drum and there is danger of burning wood.

Any motor worth having may cost you ~$200 US.  Which is a significant fraction of a whole new unit.

 

Consider offering your old machine for sale for parts on Ebay or similat and buying a Brynes machine?

[reklein]

The specs I gave are from the label on the motor. If it comes to parting out I may have to do that. I found a lead with Grainger company who deals in such thiings. I may have to remove the motor anad take it to the branch to get a new one. But yeah the MM sander has its shortcomings.

[Jim Rogers]

Check McMaster Carr

 

[Roger Pellett]

If this was my machine, I’d buy a small 110v 3600RPM  or 1750RPM AC motor and fabricate a new mount.  A new fractional HP 110v electric motor sells for as little as $100.  Jaager is correct, you’re looking for torque not drum speed, so you may need to play with pulley sizes.

 

I don’t understand why MM would sell a 12v. Machine.  My guess that it might have something to do with selling the machine internationally.

 

 This could be an opportunity to improve your machine.

 

Roger

 

 

Edited September 19, 2021 by Roger Pellett

[Jaager]

I built my vertical drum sander around a Dayton motor from Grainger.

General Purpose Motor, 1/3 HP, Capacitor-Start, Nameplate RPM 1,725, Voltage 115/208-230V AC   It is TEFC  and CW-CCW   It seems to be top quality.

It is also large, heavy and relatively expensive.   The reversing function is of no use for a thickness sander, so this is not the motor for your machine.   Grainger motors tend to be expensive and finding an appropriate one as your replacement -  a major headache at the least.  For my machine, the motor is everything I could want.   but I wonder if the Grainger customer base is corporate buyers or university grants - a base where a premium level cost is no barrier.  Given your task and the value of what you are repairing, you might should be ruthless in how much you spend on a new motor and avoid gilding the lily.

[reklein]

I think I found a replacement motor. Using the mysterious letters ZYT I discovered its a Chinese electronics company associated with Ali Baba. I found the motor with the same specs in their online catalog,so I will try to order today. Will be interesting to see what happens. Not cheap at $135 plus shipping.

[Jaager]

I tend to think in proportions, rather than absolute values in a situation like this. 

You are reinvesting about 50% of the total value in a used machine of inferior design.

For another 50% you could buy a a machine that is more reliable, better precision, and allows for a less expensive and wider variety of sanding media.

[reklein]

Jaeger,I think you are right . I couldn't get signed into Ali baba the company that supposedly deals in those motor. Grizzly has a little lathe with that motor but their tech support won't answer the phone. Its just been a cluster all 'round. So if I want another I guess I'll have to go the byrnes route. I know his rep is impeccable. Its just I'v had some unexpected expensive hobby expenses. We should probably go to  PM if we talk more about this but it may have interest for someone looking for something similar.     Bill

 

 

 

[Jaager]

Bill,

I am not shilling for Jim Byrnes or anything.  I believe that quality and realistic prices should be acknowledged and praised,  with machines that match our needs.  As for budget,  I can't make any helpful guidance.

For media, I buy rolls directly from Klingspor.  They are just south of me in Tarheelia, but UPS is everywhere.   It is my thought that your general situation is not unique and the open decision points would apply to others, exploring this scratch build universe.

If you do replace, I hold a positive wish that you get a worthwhile return, should  you sell your present machine.

 

As for the Byrnes, be sure to get spare screws et al.    A small screw top plastic container,  a 1/4-1/2" thick scrap board with holes for the Allen wrenches,  heavy duty double stick tape to fix all this to the machine base deck,  and everything is to hand - as well as a place to park screws when you change media.  If you just place them on your bench,  small parts run away when you are not looking.

[Roger Pellett]

Bill,

 

I agree with Jaager.  I still don’t understand why MM would market a 12v. Machine.  If you buy the more powerful Jim Byrnes machine I believe that you will be pleased at the additional power it provides,

 

If you don’t feel that you can spend the money why not build one.  The only purchased parts in my thickness sander are a pair of pillow block bearings, belt,and pulleys.   In my case, whenever I get rid of something, I save the motor.  Also, our local landfill segregates that sort of thing and allows visitors to take stuff for free.  You might also be able to buy a used motor, or something used with a motor for a fraction of the new cost.

 

I turned the drum for mine from Maple using the sander itself as a lathe.  Once the maple block and its shaft are mounted in the pillow blocks, set up a tool rest and spin block with the motor.  An ordinary bench chisel works fine. I glue the sanding medium, hardware store belt sander belt to the drum with contact cement.

 

The NRG used to sell a plan set for the tool and are photos of my sander here on the forum.

 

Roger

Edited September 21, 2021 by Roger Pellett

[Jaager]

I did exactly what Roger suggested.  Except that I paid a woodworker with a lathe to turn my Maple drum.

I used the old NRG plans -  at the time, there was no model scale ready made alternative.

I made it 11" long with a 9" circumference-  The available media then was 9 x 11 sheets.    The diameter was OK, but I would make it 12" long

I also used / use contact cement.  It is a positive bear to undo and clean up.   I am fairly sure that Elmer's rubber cement would hold as well.  You can clean it up using your thumb and friction.

 

I enclose the motor at the bottom.  The bottom is an OK location.  the enclosed is a very bad idea.  Leave the ends open and cut a big hole in the base and raise the unit on large rubber corks for feet.

Maybe big holes in the sides.  The motor can get hot during a long session.

 

A tapered groove/ wedge cut for the leading edge can save tearing but it is tricky to do well.  

All and all,  my Byrnes machine is the much better option if you can afford it.

[reklein]

To be sure the Micro Mark motor is DC, not sure about the voltage. Its 150 watts,1.8 amp and 4000 rpm. It plugs in to 110V and powers the motor through a rectifier.  Yes ,I do have a lathe and have just reviewed an article that describes turning it into a thickness sander. I've also seen articles turning ones drill press into a vertical thickness sander. So theres all sots of ways to go with this. I also have the tools to make this happen. So we will see what comes of this. Thanks all for your input.   Bill 

[Roger Pellett]

Bill,

 

Your machine uses about as much power as two light bulbs.  The manufacturer of the MM machine tried to overcome this by very high speed rotation.  This means that the machine produces very little torque.  In a thickness sander high RPM’s are not good since as Jaager points out it can burn your wood.  Much better to have a much slower machine with much higher torque.

 

Roger

[Jaager]

Bill,

 

To add to your stew of options:

 

Using a drill press to drive sanding drums

The motor being in your line of sight is the major negative.  In a thickness sander function - this is not a problem.  When shaping frames with a serious bevel, it can be.

If your drill press has a large steel table - a Carter magnetic fence is a quick and dirty but not low cost help to the thicknessing function.  Fine tuning the thickness gap will be difficult and tedious though.

 

There are sleeveless sanding drums that let you use off the shelf 9 x 11 sheets.

They not only come in standard 3" high with a variety of diameter variety,  but there is an additional 3" diameter drum that is 6" high and one that is 4.5" high.  The 6" is a big help for shaping frames if you favor the larger scales.

 

(Roger has covered the following - we were typing at the same time - me very slowly)

To speculate about your present machine:

The original version used a DC motor  - the  present version switched over to an AC motor.

I have no idea about physical size of  a DC motor vs an AC motor to get the same power output.

I also do not know if AC has any advantage over DC in efficiency, size and maximum possible force.

You may wish to determine the force/power difference and not replicate a possible under powered situation.

Edited September 22, 2021 by Jaager

[Bob Cleek]

16 hours ago, Jaager said:

I also used / use contact cement.  It is a positive bear to undo and clean up.   I am fairly sure that Elmer's rubber cement would hold as well.

3M makes the right tool for that job: Feathering Disc Adhesive. The 3M stuff is relatively expensive. Less expensive abrasive disc adhesives are on the market. Disc adhesive permits the easier removal of worn out discs than rubber cement, although the two may appear the same. One application of the disc adhesive will permit removing a used disc and replacing it with another without adding more adhesive for a few discs before more adhesive needs to be added. It cleans off the surface easily with acetone, or by rolling it off by hand. Sold in auto body and fender repair supply stores or on line. Here, again, the Byrnes machine has the advantage in that  less expensive cut abrasive sheets in standard sizes can be used and no adhesive is required. The savings over purchasing proprietary abrasive belts is another advantage of the Byrnes thickness sander.

 

Edited September 22, 2021 by Bob Cleek

[Bob Cleek]

42 minutes ago, Roger Pellett said:

Bill,

 

Your machine uses about as much power as two light bulbs.  The manufacturer of the MM machine tried to overcome this by very high speed rotation.  This means that the machine produces very little torque.  In a thickness sander high RPM’s are not good since as Jaager points out it can burn your wood.  Much better to have a much slower machine with much higher torque.

 

Roger

I've recently come to realize how important it is that "Torque is good. Speed is not so good." It's not just the burning issue with sanding, but it applies in all things. High speed micro-motors have become very popular in recent years. Their small size offers advantages, particularly in terms of battery powered tools, as does their lower price in some instances, but high speed cutting tools are much more difficult to control and a slip that ruins a workpiece is much more likely to occur. There are lots of cute 12 VAC cutting tools on the market now that will easily stall out if you try to hog through hard wood. They're made for cutting balsa and basswood and that's about it. While manufacturers replace torque with speed, it's not an even trade. A lot is lost in the translation.

 

Another problem with high speed electric motors is that if you slow them down with a rheostat speed controller, you don't get any corresponding increase in torque. You pretty much have to get them spinning at high speed to get much done with them in any case.

 

This is most apparent if one compares steam engines with internal combustion engines. A 5 HP steam engine will drive a 25' displacement hull at hull speed turning a large propeller slowly with its high torque. It takes a 25 HP low torque gas or diesel engine to do the same spinning a small propeller at high speed. The steam engine will last virtually forever with far less maintenance. The gas or diesel engine will wear out in relatively short order and require far more maintenance until it does. There's no free lunch.

[reklein]

I'll have to say that from the beginning the MM sander did not have much power. It would barely take off a 64th at a pass.  I'm thinking about removeing the driven pulley aand chucking up the shaft in my 3/8th Ridgid Drill motor. All kinds of Ideas about getting a free sander outta the deal. Oops didn't see that no free lunch statement.     Bill