Reversing the 1x30 belt sander

[nhamilto40]

Reversing the 1x30 belt sander

Warning: LONG

Feel free to skip down to the rewiring section.
















Disclaimer

The drawings, procedures and words shared here are for information only. Your actions are your responsibility - VERIFY and CHECK information out before proceeding, and don't attempt anything without the required skills. USE THIS INFORMATION AT YOUR OWN RISK! I reject any liability for any damages or injury caused to people or property from the use of this information or from any associated links. No claims are expressed or implied as to the safety, usefulness, or accuracy of this information.

Background

I recently picked up a cheap 1x30 belt sander at Harbor Freight (item 2485-1VGA) for $30.

When I got it home I took it apart to see how it was built. I then decided to see if I could reverse the belt direction to improve its function as a knife sharpener.

Since the belt is driven directly by the motor the motor's direction of rotation must be reversed to change the direction the belt travels.

The motor proved to be a common single phase induction motor with a capacitor mounted its control box.

The Goal

Electrically reversing the sander's motor.

Theory

All single phase motors induction motors need some mechanism to get the motor's rotation started.

The most common method is to build the motor with two separate windings; a start winding and a run winding. A capacitor is typically used to shift the phase supplied to the start winding and thus start the motor.

The start winding usually has a higher resistance since it is wound from smaller wire.

The motor can be reversed by reversing the connections of either the start or run winding.

For full details see http://www.lmphotonics.com/single_phase_m.htm

Tools and Supplies

multimeter
dykes
wire strippers
knife
hammer
#2 and #3 Phillips screwdrivers
3 mm allen wrench
dpdt toggle switch (I used a Gardner Bender GSW-16)
drill and bits
18 awg, 600V, 105 degree primary wire
crimp connectors as needed
crimper
liquid electrical tape
1/8" heat shrink
zip ties
sharpy

Practical Application

After I opened up the motor's control box I found four motor leads: white, blue, black1 and black2. The white and black1 where connected to the power switch. Black2 and the blue where wire nutted to the capacitor leads.

At this point I thought I was home free; just swap two of the motor leads to reverse the motor's rotation.

So I label all the leads and get out the multimeter. The first thing was to measure the resistance between each lead to determine which one corresponded to which winding and to deduce the motor's exact type.

After some testing I recorded the results:

lead pair ohms
black1-black2 0.4
black1-white 9.2
black1-blue 26.0
black2-white 9.2
black2-blue 26.0
white-blue 17.1

Ok now I had a problem. Since black1 and black2 where shown to be internally connected by their low resistance I really had only three motor leads (black, white and blue).

My revised test data became:

lead pair ohms
black-white 9.2
black-blue 26.0
white-blue 17.1

Now it was time for some head scratching I either had to figure out what was going on inside the motor or just give up the project.

I don't give up easily.

After extensive research (Google) I found this site

http://www.homemetalshopclub.org/news/sep01/sep01.html (scroll down a bit) where the author talks about rewiring his imported carbide bit grinder. His motor is set up differently from mine but he mentions that due to OSHA regulation these motors have been made with one end of both the start and the run windings connected internally and brought out as a single lead. He claims that this is done to prevent the user from rewiring the tool to run in the reverse direction (thus preventing injuries). He get around this by swapping the capacitor with an inductor (an inductor provide a phase shift opposite to that provided by a capacitor).

Using this new information I reconsidered my test results and concluded that I had the expected two windings. Since 9.2 plus 17.1 is approximately equal to 26.0 I had one 9.2 ohm winding between the black-white pair, one 17.1 ohm winding between the white-blue pair and the both the windings in series between the black-blue pair.

The higher resistance (17.1 ohm) winding was taken to be the start winding.

Lead connections:

black -> one end of the run winding
blue -> one end of the start winding
white -> the other ends of both the start and run windings

Now to reverse the motor I either had to get use the inductor

technique or open the motor and separately bring out the ends of the winding originally connected to the white lead.

I chose to open the motor case.

Rewiring

I first removed the motor from the grinder and then removed the plastic control box, the plastic shroud and cooling fan.

I then removed the bolts holding the motor's die cast end together and tapped the end caps off the stator laminations.

The motor's leads proved to be welded to the ends of the windings. This connection was protected by a fiber tube. I carefully exposed the white leads connection and cut off the end of the start winding.

I reconnected this end to a new red lead and insulated the new connection with heat shrink and liquid tape.

New lead connections:

black -> one end of the run winding
blue -> one end of the start winding
white -> the other end of the run winding
red -> the other end of the start winding

I then reassembled the motor, added a dpdt switch and wired is as

follows:

forward rotation

black -> hot
white -> neutral
blue -> capacitor -> hot
red -> neutral

reverse rotation

black -> hot
white -> neutral
blue -> capacitor -> neutral
red -> hot


Safety considerations:

The belt the grinder ships with is directional and will break if run in the wrong direction. Toss it and buy some quality reversible belts.

Always use care when grinding.

 

[Bill DeShivs]

This is good information! It may come in very handy, but I don't see why you would need to reverse the direction when sharpening. Why not just grind fom both directions with the belt traveling downwards?
Bill

 

[nhamilto40]

Strictly speaking you don't need to but i find it much easier to see what you are doing with the edge up.

Since using a belt sander with the edge leading is asking for trouble the belt direction needs to be changed.

 

[Bill DeShivs]

I see.
Thanks.
Bill

 

[dbreed53]

Thank you for the information on how to reverse this belt sander I have searched for more than a week to locate.

I have now done it and it works fine. However, having the time to practice with it running reversed, I actually have found it easier to control the blade with it running towards me. I am using a guide mounted on the platen that allows me to set the angle and as long as I keep the blade against the guide, the blades stays at the preset angle, at least as well as my ability to keep the knife level and flat against the guide.

With the belt running away from me, if I allow enough pressure on the belt, it sometimes pulls the knife away from the guide, thereby lwoering the back of the blade and decreasing the angle, and causes a "holiday" to occur on the edge.

I will keep practicing each way for a while to learn what I like best.

But, again, thanks for posting clear details on how to change the direction of travel.

 

[changeofseasons]

Good info. I've put a dpdt switch on two of my grinders, Viel S5 and Kalamazoo. Now if I could just do it to the Craftsman...

For anyone wondering what the benefit of this might be, it's mostly so you don't have to change the way you hold the blade when moving from grinding to stropping. I prefer to use the grinder edge leading when sharpening and edge trailing while stropping.

It's not a big deal to just do all the sharpening in an edge trailing direction, but that can produce a big floppy burr. The burr will eventually get ripped off by the strop anyway, but I don't want it flopping around and in the way while I inspect the edge between belts. Just my preferences

 

[maethor]

Thanks for the tutorial, man. I have an old Belt sander sitting around somewhere on a shelf in the basement, might just give it a try, I'll probably post some more on the project, perhaps some pictures of the finished product.

take care

maethor

 

[JamesBrauer]

I successfully worked through these excellent instructions with my new 1x30 sander from Harbor Freight.

Here are some annotated photos:

thanks
James B

 

[NRA]

Great current (pun intended) information, for a very old thread.

I find putting the sander at an angle that my knife blade is, and working it like a SharpMaker rod, to be the best way to use this machine for me.

Angle Cube dials the precise lift I need.

The hack I would like to see for this sander, would be a low speed motor.

 

[leosapprentice]

First of all Thank you this has been a great help.

I do have one question however that may seem dumb. How do you tell which of the three leads connected to the white wire is the starter lead? Based on looking at it and following the guide and photos above I believe it is the one wire that doesn't loop directly back into the bundle. However, I just want to be sure.

Thanks Again

 

[Danielgr]

My first attempt to post. I was looking for a good way to sharpen my hunting knifes and ended up with this thread. Decided to reverse the direction of the grinder as in this thread, but instead mounted it on it's back and made 3 rests 18deg, 20deg, and 22,5 degrees. Use 600, 1000 and leather belts - results are amazing.

Edit - the pictures did not post - anyway mounting the grinder on it's back reverses the direction of rotation and the belt is moving away from you at a 45 deg angle. I will figure out how to post pictures.

 

[GeneyD]

This is my first attempt to post. What colored wire goes to what terminal on the DPDT switch? And which is the start winding wire for sure ? (Cut which lead wire off the white wire, it has 3 wires) ?

 

[heatvent]

Hi, I think the person who posted the photos just reversed the direction and did not wire in a DPDT switch is my guess. Basically what you are doing is installing a separate neutral wire for the start winding and then you can reverse the blue (start winding hot) and the new neutral (red in this case) and reverse the motion of the wire. I am starting to work on doing the same thing. My motor does not seem to have 3 wires attached to the white neutral ... I only have two. So I plan to cut one and solder a new wire to it. I am not sure which is the neutral of the start winding or the run winding so I will probably have to check resistance and see and either the existing white will be my start winding neutral or the new wire I solder (assuming I cut the right one).

Disclaimer: I am no expert on this stuff, just read this thread and also watched some youtube videos so take my comments at your own risk!

You can see the two black wires going into the sheath with the blue stripes and the white goes into the one with the red strip. There are two wires exiting the red striped sheath. If anyone knows how to visually discern the start vs run wiring neutral please let me know.

 

[heatvent]

OK, so I cut 1 of the 2 wires connected to the white neutral and soldered to a new red 16 awg wire (I didn't have 18 awg). BTW, magnetic wire is enamel coated and at first the solder would not stick. I carefully scraped with an exacto knife and then used a lighter to try and melt off what was left. Seemed to work. I used liquid electrical tape to isolate the wire I left on the white neutral where I cut away the insulation sheath to get at the wires. I used heat shrink to isolate the newly soldered red wire. I ended up with one small alteration to the original poster. Since I couldn't tell which of the two neutral wires were the start vs run, I just picked one. I guess I ended up cutting the run winding so my RED is the RUN neutral and my WHITE is the START neutral, as follows..

New lead connections:

black -> one end of the run winding
blue -> one end of the start winding
red -> the other end of the run winding
white -> the other end of the start winding

Forward rotation:

black -> hot (SAME AS REVERSE)
white -> neutral
blue -> capacitor -> hot
red -> neutral (SAME AS REVERSE)

Reverse rotation:

black -> hot
red -> neutral
blue -> capacitor -> neutral
white -> hot

Now I just need to wire up the switch and clean up the wiring. My understanding of how to wire this up would be as follows for the GSW-15 switch (this is an On/On vs On/Off/On for the GSW-16...I didn't want an off it is either forward or reverse).

MAIN SWITCH

Black -> Black wire to motor
White -> Red wire to motor (on mine see above) & to Post 2 on GSW-15 switch

GSW-15 SWITCH

On Position Position 1 Position 2

Wire Capacitor Black from motor White to Motor
Post 4 5 6

Post 1 2 3
Wire White to Motor White from main switch Capacitor

This way when the main switch is on and the DPDT switch is in position 1 it should be in forward and in reverse in position 2. You have to let the motor come to a complete halt before reversing or it won't reverse.

BTW the switch if fairly big all wired up and there wasn't much room in the case so you need to likely relocate the capacitor. I will end up 3d printing a new cover that can hold the capacitor out a bit.

 

[Gray Burch]

When I attempted following the directions I was surprised to find mine had six wires. I made a diagram of the type described by heatvent & nhamleto40
I also made a schematic of the type which I have.

The schematic shows the original situation before AND what it would look like after adding a double pole double throw switch. Personally I used an Eaton switch with snap together contacts.

Here is the one described by others:

Here is the one I have -- two main coils and one starter

 

[DocWoo2]

This thread is old, but still very useful.
I recently performed this surgery on a HF 1x30 belt sander and put in a switch to reverse it. I am a retired electrician and have rebuilt many motors, so this was something I was confident doing. But I just want to confirm that the current crop of 1x30s being sold at HF have the motor with three windings, two run windings and a start winding.
To be sure which winding is which, you almost have to separate the three neutral leads inside the motor. Then the start winding can be brought out with a separate lead.
Care should be used to join the wires when connecting them within the motor. They should be soldered and insulated with heat shrink, then secured so they can't come into contact with moving parts of the motor. Use of small wire ties works well.
I put a DPDT switch inside the motors junction box. There is barely enough room, so placement will be dictated by that. One warning, in case you don't realize it initially, DO NOT EVER try to change the direction of the motor (operate the DPDT switch) while the motor is running. It must be off and at standstill when you move the switch.
I accidentally bumped mine and tripped the breaker in my house panel and it blew out one contact in the switch! Luckily, I had a spare switch.
You could also just wire the motor in the reverse direction permanently and avoid the possibility of accidentally hitting it, if you only want to ever use it in edge-trailing direction.
I have been using this grinder for a leather belt almost exclusively. The higher speed doesn't hurt for stropping and I can leave the platen set up for the thicker belt.
I have a second HF 1x30 that I replaced the motor with one of the variable speed sewing machine motors, but that's a different topic.