converting spindle sander

Keye

Keye
Corporate Member
What is the chance of converting a 4.5 inch spindle to a 6 inch spindle. I have a Sears model that is close to 20 years old. I have looked for a new sander but not a single one gives the length of the spindle in the specs. If you look hard enough for the sleeve size you can determine the spindle lenght. I have yet to see a spec for the length of travel.
 

zdorsch

Zach
Senior User
How big is the hole in the table where the spindle comes through? I think this is a limiting factor.

The drum that holds the paper is a composite of some sort, I think, and probably does add much weight as diameter increases. Although I’m sure someone better versed in physics will worth the me if I’m wrong about this!
 

Oka

Oka
Corporate Member
Just reading this what comes to mind is increase in inertia mass (6" vs 4.5" dia), this most likely lesser of an issue for the motor than the friction vs torque output.

Most Machines (Especially Craftsman) misrepresent the true power output of the motor, thank marketing for this. This marketing deception is rampant EVERYWHERE. Us buyers need to be informed or we get duped. The other place we see huge deception is in Lumen ratings in light bulbs......:mad: FYI 746 watts= 1 hp roughly 7 amps to 1 hp. Keep in mind all motors run between 85-90% efficiency so, in order to get a true one hp it needs to be 1.1 hp or 8amps/120 volt rated motor.......... All this is lab calculations not real life but it gets you some starting points to work with.
That said, if the motor power is ample to resist the increased friction, then it would work ok. Bear in mind the old 4.5" dia has a roughly 14" surface area and the 6" will be about 19" surface area.
Without getting into a bunch of math, this is what will increase the work burden on the motor. Surface area. The increased inertia from this will be the lesser impact on the motor except for the startup impact.
My own real life experiences have showed me if the motor is a true 1hp motor, it would work ok (assuming it is a 1to1 direct spindle) above that, you will be able to hog in on the work if that is the need, below that, you will be going slow and lighter push based on the slowing sound of the motor, and will shorten the life of the motor. Damn, I planned on writing just a couple of sentences.....
 

bob vaughan

Bob Vaughan
Senior User
I think spindle height is the issue, not diameter.
If the sanding spindle is removable like a lot are, then its merely a matter of having a new one made to your specs.
My sander uses 9" tall spindles. Often the 4.5" tall sleeves are available on sale so I made some spindles to take the shorter sleeves.
I think a lot of spindle sanders have a 1" stroke cycle except maybe the little plastic bench top things. Don't know about them.
 

sandfarm

Joe
User
Mine is an old Boice Crane that uses 9" spindles. I made some 6" ones for smaller than 3/4" diameter.
I don't think the size makes much difference on the power.T
This one has an oscillating stroke of 7/8".
 

Keye

Keye
Corporate Member
Thanks for the replies. I am a retired engineer so all of this does make sense to me. I have not been able to find any info which indicate if the spindle is removable or not. The nut which secures the sleeve in place is reverse thread. For those who have removed a spindle was yours reverse thread?

The knob on the hold down nut is bigger than the 3/4" sleeve. This means I can not use any sleeve less thank one inch on any thing greater than 4.5:"deep. I am not able to go out and about so I can not look for something which might solve this. July will be 12 months since my surgery and my surgeon says this will end my recover period. Pretty sure this virus would be a death sentence for me so I am not taking any chances, as if the boss(my wife) would let me
Sure happy I have woodworking and fishing or I would be crazy by now.
Stay safe!!
 

bob vaughan

Bob Vaughan
Senior User
Getting over the nut on a sander can be a problem so don't use a nut. These small diameter spindles shown below use a hose clamp at the bottom and electrical tape at the top. If the abrasive has a good x-weight back to it, it can be wrapped around the spindle shank and taped at the top. This works for me when I've got to get over a small hole. If you wrap the abrasive the wrong way the sander has subtle ways of letting you know this. These photos should give a good enough idea so you can take it from here.
1 sander spindle - 1.jpg1 sander spindle - 2.jpg1 sander spindle - 3.jpg1 sander spindle - 4.jpg1 sander spindle - 5.jpg1 sander spindle - 6.jpg
 

Keye

Keye
Corporate Member
One more thought before I stop beating this dead horse.
Would it be feasible to have an extension made to screw onto the existing spindle? I would not be surprised if someone has done this.
 

bob vaughan

Bob Vaughan
Senior User
Give us some images to work with and maybe a schematic. Part and stock numbers would be meaningless. Without knowing what we're facing, we'll be just wasting our time taking stabs in the dark.

What you ask is likely to be do-able with blueprints (design drawings) from a retired mechanical engineer maybe.
Some will depend on the expertise of the machinist considering executing what the drawings call for.
 

Keye

Keye
Corporate Member
The guy who rents my barn and pastures came by to pay his bill. His family has been in this area for generations. I figured he might know someone with a small shop who could help me. I know he works for a company which does high tech defense contract work for the government. I did not know they make specialty high tech components from metals I have never heard of. I explained to him what I am trying to accomplish. He said no problem, he would have one of his guys make what I want this week. I have a micrometer so we took measurements and he took the hold down knob so they can make the threads correctly.

I am still surprised something like this is not available for purchase.

I can see the 3" spindles being a problem for the motor due to the added mass but hopefully the smaller ones will not be a problem. If the additional surface area of the of the taller spindles overloads the motor and caused it to fail I will just have to buy an upgrade:D.
 

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