LumberJocks

Table Saw motor RPM reduction

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by GemStonePens posted 02-26-2014 08:20 PM 2727 views 0 times favorited 21 replies Add to Favorites Watch
View GemStonePens's profile

GemStonePens

4 posts in 1229 days


02-26-2014 08:20 PM

Topic tags/keywords: disc sander rpm reduction table saw motor modification question

Hi. I am in the planning phase of making a disc sander using the motor from an older bench top table saw. My question is would the speed of the table saw motor be too fast for this use and if so is there a way for a non-electronic understanding person to either reduce the RPMs for good (I do not have the knowledge base to re-wire or take the motor apart) or a variable type switch that I can connect to the motor that would allow me to speed up or slow down depending on what I am using it for?

Thanks.


21 replies so far

View gawthrrw's profile

gawthrrw

206 posts in 1906 days


#1 posted 02-26-2014 08:24 PM

Im not an expert either but im pretty sure that would be to fast for a disk sander. The other thing I would worry about with slowing the motor down is it overheating.

-- Rob, Dallas TX

View TheDane's profile

TheDane

4997 posts in 3122 days


#2 posted 02-26-2014 08:34 PM

I wouldn’t mess with it … a universal motor like they use in most bench-top tablesaws (5400rpm) runs way too fast for use in a sander. You would be better off to pick up an induction motor (3450rpm).

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View MT_Stringer's profile

MT_Stringer

2847 posts in 2690 days


#3 posted 02-26-2014 08:39 PM

Is it direct drive or belt driven?
A smaller pulley on the motor shaft would under drive the sander end thus making the sander disk turn slower…or maybe this doesn’t apply to your set up.

-- Handcrafted by Mike Henderson - Channelview, Texas

View woodbutcherbynight's profile

woodbutcherbynight

2408 posts in 1868 days


#4 posted 02-26-2014 08:53 PM

+1 MT_Stringer smaller pulley setup will reduce speed.

Harbor freight has a entry level disc sander for $59.99 if you get a coupon even cheaper, item # is #97181
link

If you are just into building one for the sake of doing so more power to you several here including Bearpaw have made some interesting sanders and such. If you just want function at a decent price this option is not bad and will manage well for most hobbyist.

-- Live to tell the stories, they sound better that way.

View bigblockyeti's profile (online now)

bigblockyeti

3663 posts in 1180 days


#5 posted 02-26-2014 09:05 PM

Do you have a picture of what you’re working with or a make a model of the saw the motor came from? What diameter sanding disc will you be using?

View GemStonePens's profile

GemStonePens

4 posts in 1229 days


#6 posted 02-27-2014 07:46 AM

Thank you for all the advice and here’s the clarification:
@MT_Stringer It’s a direct drive motor. The saw is a Home Depot Ryobi 10 inch BTS 15. The sticker says 120V-60Hz-15A-4800 rpm.
@woodbutcherbynight you make a good point about other options, but yes, I’m really trying to use what I have to make the sander since it’s sitting on the floor collecting dust. I already have a 6 in Craftsman sander and find it’s just not powerful enough or large enough.
@bigblockyeti I don’t have much to take a photo of just yet since I’m still trying to formulate a plan and trying to figure out if I can/should do this. The idea is to make a 10 inch disc sander or perhaps by using a 12 inch disc the extra size might help to slow it down since it’s a 10 inch table saw motor?

View bigblockyeti's profile (online now)

bigblockyeti

3663 posts in 1180 days


#7 posted 02-27-2014 02:01 PM

The extra size is very unlikely to slow the motor down, 4800 rpm will be way too fast for a 12” disc, most dedicated sanders with a 12” disc will spin between 1725 and 1750 rpm. To safely slow the motor you could use a router speed control, the kind designed to control the speed of an otherwise fixed speed router. You will certainly want one with a 15A rating given the power requirements of your saw motor.

View JoeinGa's profile

JoeinGa

7472 posts in 1466 days


#8 posted 02-27-2014 02:13 PM

Here’s the one I made. Started with a motor that was way too underpowered, tried another that ran at 3450rpm. WAY too fast. Ended up with a 1750 rpm motor that is Just right!

(hmmm, starting to hear the story of Goldilocks in my head)

Anyhoo, see it here…
http://lumberjocks.com/joein10asee/blog/34349

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View GemStonePens's profile

GemStonePens

4 posts in 1229 days


#9 posted 02-27-2014 02:35 PM

@bigblockyeti Thanks for the information. The router speed control sounds like the way to go since I want to try to use this motor. I’m ure buying or finding a motor with lower RPMs would be the best bet, but I think I’ll give this a go 1st.
@joein10asee That’s exactly what I am looking to do. You did a great job! I’ll use yours as my “benchmark” for success!

View woodbutcherbynight's profile

woodbutcherbynight

2408 posts in 1868 days


#10 posted 03-02-2014 05:00 PM

I liked joein10asee story

-- Live to tell the stories, they sound better that way.

View Shawn Masterson's profile

Shawn Masterson

1297 posts in 1408 days


#11 posted 03-02-2014 10:49 PM

Being a universal motor you can dial the speed wherever you want with a cheap speed controller.

I totaly understand your point of view. why not use it instead of leaving it to rot.

View TheDane's profile

TheDane

4997 posts in 3122 days


#12 posted 03-02-2014 11:05 PM

Hmmm … I wonder how much loss of power you would see by using a router speed controller like the one Shawn Masterson linked to?

If I recall, the horsepower rating on a universal motor results from the higher RPM. If you check that down with a rheostat, I wonder if it will have enough umph to spin a sanding disk?

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View runswithscissors's profile

runswithscissors

2172 posts in 1484 days


#13 posted 03-02-2014 11:22 PM

The Dane has a point about loss of power with electronic speed reducers. But if you want to try it, a 15 amp reducer is really marginal. Better a 20 amp model. It will cost a bit more, of course.

I’m not sure who sells them, but there is a 10 metal abrasive disk made just for table saws. In fact, I have one kicking around somewhere.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Dallas's profile

Dallas

3599 posts in 1946 days


#14 posted 03-02-2014 11:49 PM

If you still have the parts of the saw, especially the arbor, (where the blade bolts on), it is connected to the motor with a gear set.
With my old BT10S, I took the little gear box apart and swapped he gears around. That slowed the morot to about 1725 rpm.
Then hooked a pulley to the arbor and another to the arbor I used for my spinning shaft. That brought the speed down to 800 rpm at the arbor I am using.
I am building a small wide belt sander with it, if I ever get back to it.

One thing I found when using the HF router speed control…. the motor loses a lot of torque and will stop with very little effort applied to it.

-- Improvise.... Adapt...... Overcome!

View Ingjr's profile

Ingjr

144 posts in 2475 days


#15 posted 03-02-2014 11:55 PM

Your 15amp universal motor shouldn’t have any problem turning a 10” sanding disc with a HF speed controller. Works just fine with a router which is basically the same motor set-up. Lot less of a drag on a sander than a 10” table saw rip blade.

-- The older I get the faster I was.

showing 1 through 15 of 21 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com