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saltytri
10-22-2017, 06:47 AM
This buffing machine has proven to be a useful and safe addition to my shop. The photos show the general layout of the machine and ought to make it obvious that anyone who can put an ukulele together can probably build a similar machine at less than the cost of a commercial unit. My original post provided a list of parts and suppliers to help others of figure out what to buy and where but, after some interesting discussion concerning possible safety issues, I don't want to be responsible for what anyone else might do so I've deleted all references to particular parts, dimensions and design decisions.


https://farm5.staticflickr.com/4478/37599358880_ed5e6c17ca_c.jpg


https://farm5.staticflickr.com/4461/37808482986_4594de5f61_c.jpg


For many builders, it would be a good idea to extend the shaft so that buffs can be mounted on both ends. This just won't work in my shop because of severe space limitations but the value of having a buffer at all made it worthwhile to me to build it as shown. This means that it is necessary to change the buff for each grade of compound but this is easy and a small price to pay to enhance my ability to produce quality glossy finishes.


https://farm5.staticflickr.com/4468/37929750741_42bb2ca6aa_c.jpg


https://farm5.staticflickr.com/4449/24078709778_cf9bc38d3d_c.jpg

mzuch
10-22-2017, 07:39 AM
Thanks for posting. I'm in the same boat re: lack of space, and I've been wanting to do this for some time. Question: How much did the parts cost in total?

Moore Bettah Ukuleles
10-22-2017, 07:42 AM
Nice job there. My shop is very small as well but I really need two buffs. I solved the space problem by mounting mine on the end of my bench on a large hinge so that it swings out of the way when not in use.

saltytri
10-22-2017, 07:43 AM
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saltytri
10-22-2017, 07:58 AM
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Timbuck
10-23-2017, 12:17 PM
Nice job ..I made a spindle to fit on the back of my lathe headstock to hold a buffing wheel ....it worked well with lots of different speeds to choose from...but up to now I've never used it.

saltytri
10-24-2017, 06:49 AM
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Moore Bettah Ukuleles
10-24-2017, 07:17 AM
Good idea, Ken! I should have done that with my lathe so I could buff at my max spindle speed of 3000 rpm. That would have been interesting. :rolleyes:

Hope you and Mrs. T feel better soon.

I find that about 800 RPM on a 14" buff to be the ideal speed for me. Much more than that and I'm asking for trouble.

Jim Hanks
10-24-2017, 07:28 AM
And only use it outside. Take my word for this.
Sounds like a good story hidden in that sentence. :p:rolleyes::p

saltytri
10-24-2017, 07:52 AM
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saltytri
10-24-2017, 07:57 AM
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sequoia
10-24-2017, 07:23 PM
I don't mean to be a Debbie Downer here, but just the voice of caution. Buffing machines can turn into "ukulele launching machines" that can shoot out an ukulele at amazing speeds through the air and into the wall at the other side of shop in a split second with profound and disconcerting effects upon the instrument. (Sob!) This has never happened to me, but I've heard a few horror stories and the results were not pretty.... Me, I just use my hand. Surface Feet per Minute is about 120 I reckon. Possibility of the ukulele launching itself into space: 0. Bumper sticker: Real luthiers do it with their hands.

saltytri
10-24-2017, 08:08 PM
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kkimura
10-25-2017, 05:03 AM
Very nice workmanship. But, for safety sake, the bearing needs to be closer to the buffing wheel by at least 50%. It's all too easy for that much unsupported mass to start whipping in a large arc if the shaft starts to bend while spinning.

saltytri
10-25-2017, 05:55 AM
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Timbuck
10-25-2017, 06:00 AM
Very nice workmanship. But, for safety sake, the bearing needs to be closer to the buffing wheel by at least 50%. It's all too easy for that much unsupported mass to start whipping in a large arc if the shaft starts to bend while spinning.

I think the 1" shaft at the slower rpm's that these devices run at will be ok Tho I dont know what this ones speed is...It's very similar design to the ones marketed by StewMack here http://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Finishing/Buffing/StewMac_Guitar_Buffer_Complete_Outfit.html http://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Finishing/Buffing/StewMac_Guitar_Buffer_Complete_Outfit.html

saltytri
10-25-2017, 06:12 AM
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Moore Bettah Ukuleles
10-25-2017, 07:51 AM
I agree that at first glance the buffing wheel would seem less dangerous if it were positioned closer to the bearing. But I'm not an engineer. The thing I don't get is why you went through all that work and didn't bother to mount two buffs. It looks like the shaft is long enough where it could easily be shifted to accommodate two buffs. It's so much easier than having to stop and change buffs. Of course in the case of two buffs you'd have you relocate the entire assembly but it could be extended off the end of the bench, or hinged like mine is.

saltytri
10-25-2017, 09:32 AM
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kkimura
10-25-2017, 11:16 AM
I'm aware of the phenomenon and the concept of critical speed. As far as I am able to figure, my shaft speed is less than critical speed by a factor of at least 5.

Lacking engineering expertise, I used the LMII/ShopFox unit as my guide:

http://www.lmii.com/products/finishing/buffing/shopfox-buffing-assembly

The shafts are 3/4" in both cases. My shaft is 1.5" longer from bearing to buffing wheel but uses smaller and lighter buffs. My shaft is supported by bearing spacing that is longer than in the ShopFox unit.

If anyone has the ability to do the actual calculations, or has real world experience that bears upon this issue, please let us know!

I don't know what "critical speed" is or how to calculate it as it never came up when I was a tool and die maker. What I worry about is shaft balance and the effect of increasing radius on balance.

Here's a rough test, if the shaft bends at all when you push on the buffing wheel, you may have a problem.

A shaft and wheel assembly that doesn't vibrate at 1000 rpm is in balance. If the wheel can move off center while spinning, it's off centered weight will cause the assembly to be out of balance. Furthermore, and herein is the real danger, centrifugal force will pull the wheel further off center until you have a bent shaft and a buffing wheel swinging in an arc at 1000 rpm. I have seen this happen on engine lathes with inadequately supported shafts that were over extended from the chuck. When it happens it happens almost instantaneously.

If your shaft doesn't deflect at all when you push on the buffing wheel, you may be safe.

Michael Smith
10-25-2017, 02:39 PM
The shopfox buffing assembly for around $95 works perfectly fine for me and has two ends. Not too hard to come up with a 1725 quarter horse motor. Some tools are not worth making yourself.

resoman
10-25-2017, 03:16 PM
Ditto on the Shop Fox. Works great for me

saltytri
10-25-2017, 03:46 PM
Some tools are not worth making yourself.

I don't recall ever suffering from the notion that there is something inherently noble about building tools. Heck, I even buy expensive single purpose doodads from StewMac if they do a job that I need to do. The ShopFox and StewMac buffers are fine if they meet your needs. I considered both and even looked at the ShopFox in person but, in ways that are important to me, neither one meets my needs so I built my own. Maybe someday another of our UU sisters and brothers will be in the same position, will come across this post, and will find my design to be helpful.

Kekani
10-27-2017, 01:55 PM
Oddly enough, I have a StewMac, and was considering UPGRADING to one like yours. Like Chuck stated, two sided, and with a 1" shaft and 14" Jescar buffs. Your's gives me some ideas. Thanks!

Note: for space saving, my motor hangs underneath. . .

saltytri
10-27-2017, 02:36 PM
Note: for space saving, my motor hangs underneath. . .

That's some good problem solving!

Kekani
10-27-2017, 03:14 PM
That's some good problem solving!

You should see the stand its on. Solid framed with 2x4, cut at angles on the miter saw, because I can. Belt tension is from motor weight, which is on a hinged base. I need bigger wheels to roll it off to the side- will do that when I upgrade.

For conversation, I'm thinking 1" shafts with circle clamps (off Amazon) instead of threaded shaft, just for ease of build. Now I have a project after the UGH Exhibition. After the vacuum press of course.

Moore Bettah Ukuleles
10-27-2017, 06:06 PM
My arbor and buffs are mounted on a 2" X 12" X 24" that are attached to the end of my bench with large gate hinges. The motor mounts on the bench itself. When I need to buff I swing the assembly up, attach the brace (also hinge mounted) and attach the pulley to the belt. When not in use it folds down out of the way. I got the idea from the many luthiers who wall mount there buffers that also have the capability to fold down when not in use.