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

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opie_7afe

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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.

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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.

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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...

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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.

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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!

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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.
DIN1481%2BISO8752+Heavy+Type+Slotted+Spring+Pin%28Spring+Tension+Pin%29_0_detail.jpg


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!
 
Brilliant write up Matt! I kinda want to run out to Lowes and do this. I do not even have a rotary yet lol.
 
they do have threaded studs to so you don't have to cut the bolt. Not sure if they have that thread size though.
 
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?
 
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!!!
 
Matt,

This thread is absolutely spectacular!! :props:

I enjoy the step by step illustrations and instructions and will get started on my own thanks to you!! :dblthumb2:
 
Matt,

This thread is absolutely spectacular!! :props:

I enjoy the step by step illustrations and instructions and will get started on my own thanks to you!! :dblthumb2:

:iagree: Nice DIYer, along with a $$ saver!

I'm thinking about making one, or more, for myself...

But since this adapter will be exposed to a "wet environment" with a lot of 'chemical use'; along with, "heavy-duty" usage at times....I'm going to use: "Grade 8" Stainless bolts/(or studs)/hex couplings....may be just a little more costly upfront, but they should last a lifetime (at least the rest of mine).

:)

Bob
 
Sweet!!! I definitely need to make me one of these. Thanks for the tip. :props:
 
I would be afraid that it will blow apart at 1800 RPM's. But that is just me.
 
that's why you drill it out and use a roll pin in there, wont come apart with a roll pin in there...but hey each their own, remember though with the direction the rotary spins it really cant come apart as the rotation would if anything make everything tighter... i don't see the shaft breaking either especially if you use the right supplies...
 
But since this adapter will be exposed to a "wet environment" with a lot of 'chemical use'; along with, "heavy-duty" usage at times....I'm going to use: "Grade 8" Stainless bolts/(or studs)/hex couplings....may be just a little more costly upfront, but they should last a lifetime (at least the rest of mine).

:)

Bob

Bob,

I'm going the stainless route as well. Fine minds think alike! :props:
 
that's why you drill it out and use a roll pin in there, wont come apart with a roll pin in there...but hey each their own, remember though with the direction the rotary spins it really cant come apart as the rotation would if anything make everything tighter... i don't see the shaft breaking either especially if you use the right supplies...


Not worried about it coming apart. The centrifugal force on the hex nut would concern me. Not knocking your idea here at all but just expressing a personal concern. :props:
 
i wish i could have gotten stainless, my lowes sucks for the small parts hardware section, most stuff is mixed up or not what it says it is ect otherwise i would have went stainless as well lol it was my original plan. wish i had a ace hardware in this town.i hightly doubt this thing would blow apart look at the adapter that is not made by optimum its the same basic design as mine. i know the optimum one is machined from what looks to be aluminum. but if you dont feel its safe thats on you, i feel its perfectly safe. there is no way this thing could "blow up", metal has a high tensile strength and there should be now way it blows up or comes apart as like i said with the rotation the rotary has it would tighten it not loosen it, i wish people would stop doubting my ideas, just because something is not purchased does not mean its not as good as the purchased item, if not small machine shops would not be in business. however for the ones who are doubting this i will take a video when i get my adapter back (had my father inlaw bring it to work to use a drill press to drill the hole) and i will crank my rotary up to maximum speed which is 3700 rpm before i use it which was my plan anyways just to be 100% sure the roll pin wont shoot out and mess stuff up.
 
I would be afraid that it will blow apart at 1800 RPM's. But that is just me.


:iagree: I would be afraid that chinese bolt would break

I had a freind make me one on a lathe. Solid stainless :)
 
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