A tiny triple sanding station
The missus bought a new fan for the living room the other day leaving the old floor-standing 3 speed fan just begging for a new use. So I've come up with a tentative design for a tiny sanding station with a 75mm disc, a 10mm belt, and a 50mm dome mop.
The sketchup file can be downloaded by anyone who wants and a link to my sketchup files is always visible in the right hand column.
When announced on the UKworkshop Scroll Saw Forum the general feeling was that it would be sadly under-powered but bearing in mind I specifically wanted it for sanding pieces of intarsia projects I thought it would be in with a reasonable chance since whether it's underpowered or not depends on what it's intended to do.
I got the missus to take a couple of minutes worth of video of me using the motor to spin a couple of rough cut laminated MDF discs while I trued them up to make the sanding disc. And from having done that I'm pretty sure it's not going to be terribly underpowered bearing in mind I've sanding most of my parts with nail files up to press.
Intarsia is typically made up from pieces of wood the size of your thumb (or even a good deal smaller) and trying to sand those on a regular machine is far too nimble-fingered a job for me. I don't have a lot of strength in my hands nowadays and also have difficulty handling small pieces, so unlike most people who are happy to use a dremel for this sor of sanding I wanted something that left both my hands free to handle the work piece. I really fancied using the fan's oscillation mechanism to incorporate a 6mm diameter spindle sander, but on investigation it was a broken and jammed oscillating mechanism that led the missus to get another fan in the first place. It'd be very easy to implement though if I ever need to build another.
I've made a little bit of progress over the last couple of days. The disc sander part of it in fully functional and already had quite a bit of use. As regards to it being under-powered, I'd say 60W is about the very least you can get away with, it would have been nice to have another 60W in reserve but for what it's intended for it's adequate if not sensational.
Although tiny by anyone's standards it would have been smaller still if I'd had some 8mm ply laying around instead of 18mm MDF. The scale of the MDF compared to the sander as a whole does bring Isambard Kingdom Brunell to mind but then I always did admire his stuff and unlike many more recent constructions it's still around today for us all to marvel at.
This short video shows what I've done so far in action...
The next step was to cut drill and shape a small piece of wood to act as the belt sander's roller tensioner.
The belt will be tensioned automatically with a small compression spring allowing instant belt changes and self-re-tensioning in case the belt stretches with use.
The video below shows the finished belt sanding tensioner in this photo actaully operating.
I've been asked exactly how I made the belt sander rollers. The top roller (shown above) is nothing more than a couple of 8mm ID ball races super-glued onto an 8mm harwood dowel. A standard 8mm ID bearing just happens to be 5mm wide and the belt is 10mm hence the need for two.
The bottom roller is a 10mm long piece of 18mm hardwood dowel with a 10mm hole through it in which site a couple of 4mm ID flange bearings. This roller was crowned slightly before I parted it it off to provide the belt with a means of self-aligning itself correctly. The choice of flange bearings was simply because I already had some and they too are held onto the wooden roller with super glue.
The drive roller is yet another short length of 18mm hardwood dowel drilled to fit the motor shaft and held in place on it with nothing more glamorous than contact adhesive. At 60W it's a very low power application and it appears to hold just fine.
The dome sander is attached to the shaft with an M6 screw making it really easy to swap out for a flap wheel (or whatever).
I have to say that this 240 grit sanding dome is absolute rubbish. It may be ok for sanding your nails (at a push) but I was hoping it would be able to dish out small hardwood parts and it hasn't got a cat in hell's chance of doing that. It does however only attach with an M6 screw directly into the end of the shaft so replacing it with some other means of dishing out should be easy enough and there are plenty of other options to choose from and it will will eventually be getting replace with one of these:-
To summarise; I can't honestly say there's any noticable difference between the three speeds. As a fan the speed difference was very marked but as a sander you'd be hard pushed to notice it.
It does however work extremely well and is in constant use for finishing intarsia parts.
That's about all I can think to say about it so I'll shut up now. :-)
The final video:-