Electronics > Projects, Designs, and Technical Stuff
Speed modification
davelectronic:
Hello out there to the community.
Think I've chosen the correct section to post this in.
I'm trying to find a way to slow down a hand held belt sander. I think it's a universal series motor of 800 watts, on the tool handle is a small control wheel that goes from 1 - 6 for speed. Although 1 on the wheel is reasonably slow, I could do with Slowing the belt down a little more. It's for standing flat some heatsinks I have, these had a raised portion which I cut off. So need to flat the face off. I don't have access to a lathe unfortunately, Slowing the sanding belt speed will give me better control for final finished surface of these heatsinks.
Been thinking about DC of 50 - 60 Volts, but the tools speed control wheel has got me wondering, I don't want to destroy the tool before I've even got started. My supply mains voltage is 240 Volts AC at 60hz single phase. Any thoughts how I can slow this tools belt just a little more would be of great help.
Thanks for reading, any ideas appreciated.
I've attached a picture of this belt sander, it was cheap as you can see.
davelectronic:
So no replys :( Anyway I'd forgot that i purchased a reasonably high powered boost converter some time ago now. It was for another project that i never got around to. Cautiously i wired up this boost converter, the power source being a server power supply converted for bench use. So 12 Volts source, and 460 watts. I have bigger higher powered server psu, but though that was powerful enough with the lower voltage. Starting at 24 Volts, nothing, 30 Volts, nothing, 40 Volts gets it going. But this was to slow, pressed on up to 50 Volts now, and sort of ok. But still a shade to slow, i know as the voltage climbs my expectations on current begin to diminish.
I used two multimeters, one for voltage the other for current beingdrawn from the converter. I know i should have had a current reading from the boost converters input. But i didn't measure that ??? But when i set it up again, before project box time, i will test the current at the input to the boost converter. What i ended up with was 60 Volts, drawing 2.5 - 3 Amps from the boost converter. The heatsink was always touchable, so below 60° C i guess, a pro would have set up a thermal measurement reading. The 40mm fan spun up a few times, but not that much. I was aware of tool temperature, as the fan in the belt sander was running much slower at 60 Volts. But all seemed fine, the sander got warm at best. The process of facing off large processor heatsink with a belt sander does not achieve the tolerance needed for cpu cooling. But my objective is to passively cool a large transformer, buy bonding the heatsink to the transformers outer surfaces. I've found one thermally conductive epoxy, but not sure if its suitable for the purpose. If not i will create some fine copper particles and mix with suitable epoxy at time of bonding.
Ignoring the location ;D the image shows the knocked up assembly, its 60 Volts, and no one was going to come in contact, other than me, i know not best practice...
But acceptable results i think. The boost converter is largely over rated in its listed advertising. This one came off Amazon, claiming 1500 watts, err no, definitely not. There is a really good you tuber that tests buck and boost converters, most of those available from Amazon and Ebay.
I'm only posting the results, as its a viable option, staying with in reasonable parameters.
Thanks for reading and looking in. Hope its useful to someone.
Nominal Animal:
I've modded some PC heatsinks -- cheap aluminium ones, mostly originally older style processor heatsinks; like Arctic Alpine M1 --, but only by hand: using a hacksaw for the bulk removal, then various grades of sandpaper-on-mirror, with 400 and higher grades with mineral oil as a lubricant. The mirror surface is absolutely flat, so ensures the flatness of the heatsink as well.
If you have access to a woodworking bandsaw, you can use that instead of a hacksaw for the bulk shaping of aluminium heatsinks.
mikerj:
Agreed, a belt sander isn't going to give you a very flat surface and the finish won't be great either. Wet and dry paper on a piece of glass is the way to go, I usually use WD40 or similar to lubricate the paper.
Nominal Animal:
(Yup; I've only used mineral oil ("parafin oil") as a lubricant, as that's what I have (I oil my wood work surfaces with it, so always have some), and didn't have anything better like WD40 at hand.)
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