How-To: Make Your Own Rotary Backing Plate Extension!

opie_7afe · 12-03-2011, 09:19 PM

so, i was wanting a rotary backing plate extension and didnt want to place and order just for this one small thing. off i went to lowes and came home with the following supplies:

One-Coupling Nut 5/8-11 threads
One- 5/8-11 x 3 inch threaded bolt Or 5/8-11 threaded rod.
A way to cut the nut and bolt. i used a 4.5" electric disc grinder with a metal cutoff wheel
A vice or some way to hold the bolt and nut.NOT YOUR HANDS IT GETS HOT!!
measuring tape
permanent marker
safety glasses
leather gloves to protect hands.
dust mask.
Total Cost For Material: $3.97 before tax
Now the fun begins!

Here is the Bolt and Nut pictured below, Measure 1-1/2 inches on the threaded portion of the bolt and make a mark with your marker. Now measure 1-1/2 inches on the Coupling Nut and make a mark. This is where you will make your cut.

Now you take your grinder or hack saw or whatever you are using and make your cut on both pieces. Cut them all the way through then let them cool.

Now that they are cooled I like to make sure the cuts are nice and level and I mounted my grinder in the vice and held onto nut or bolt and grind the parts nice and flat. Then I take the nut and make it look like the nice factory finished side of it(no sharp points and won't cut your hand). The Bolt I just make the cut side flat. Now I change discs to a sanding flap disc with 240 grit to do final smoothing of the parts you sanded.

Now pictured below you have your 2 cut pieces of metal all ready to go and mount, However before you mount it to the polisher its good to screw each part together on the cut ends to make sure it screws in correct every time...

Ok so here is the easy part! Put the coupling nut on the rotary's spindle first and tighten it down. Now take your threaded piece of bolt put in with the cut end going inside the coupling nut and tighten the bolt by hand tight as possible.

Now don't that just look great?! I think so, But it is missing your backing plate which you screw on as normal and tighten it up as normal. You are now ready to start polishing!

This should not come apart while polishing but for me i'm doing an extra step and drilling out a small hole through the coupling nut and threaded rod and putting in a spring pin, One of these looks like the picture below, You insert the pin in the hole after you cut it down and it puts tension on the surrounding parts.

Another good reason to make your own extension is because if needed you can make the extension longer provided you used a longer piece of threaded rod or bolt. For most people a 1.5 inch extension should work great. You could use this as a double sided pad adapter but you might want to cut the bolt down shorter. I dont use double sided pads and don't think i will so i do not know the measurements. I like the threads as long as they are way better then i like the looks of the pre-made ones, Reason being is more of the threaded portion is inside the backing plate vs the ones already made double sided pad adapter.

I hope this helps others out there and provides some useful information for others as well. If you have any questions don't hesitate to ask here in this thread! Good luck to everyone and remember Safety First, Use Personal Protection Equipment! Trust me I know metal is not fun getting in the eye or metal dust in your nostrils and your tasting pennies all day!

**tw33k2514** · 12-03-2011, 09:30 PM

Brilliant write up Matt! I kinda want to run out to Lowes and do this. I do not even have a rotary yet lol.

**Ron Atchison** · 12-04-2011, 12:18 AM

Great idea! An alternative to the roll pin would be red loctite.

**Setec Astronomy** · 12-04-2011, 12:27 AM

Originally Posted by rzatch

Great idea! An alternative to the roll pin would be red loctite.

Yeah, that's what I would have done, too. Can you even get roll pins out in the world (like at HD or Lowe's)?

**Ron Atchison** · 12-04-2011, 12:29 AM

Yeah at Lowes at least they are in the hardware section.

**TS656577** · 12-04-2011, 01:03 AM

they do have threaded studs to so you don't have to cut the bolt. Not sure if they have that thread size though.

**TS656577** · 12-04-2011, 01:05 AM

BTW, well done Opie. Question for anyone. I know this is for a rotary, and I know it can be done for a DA material wise, but would this change how the counterweight works and alter the performance of the DA?

**c5z06camaro** · 12-04-2011, 01:17 AM

wow! great write up! i guess im going to lowes tomorrow.

opie_7afe · 12-04-2011, 01:24 AM

thanks for the compliments guys, i would have used the red loctite just for me i always underestimate my abilities so to combat that i usually over-build stuff LOL. yes they do have threaded studs but i could not find one in the size or thread pitch i needed, i was looking for a locking stud but could not find one of those either. you could make one for a DA using the same method just use a smaller piece of threaded rod and a smaller coupling nut, i think DA uses 5/16"-24 for the threads...might work but if you use your DA without the handle then you could chance a finger going into where the counter weight spins.making an extension for the DA shouldn't effect much if anything. if it did the edge DA adapter would not work.....i cannot wait to get my DA in a few weeks!!!