Ok, I'm struggling with the methodology towards ensuring that a small faceplate I need on my pickup winder runs 'true' (true here being no/little runout on the vertical suface). This is because a guitar pickup will affix to the face plate ...& fine copper wire feeds (0.1mm) onto the pickup - ideally I'd like runout to be below 0.1mm
Previously, I made a small faceplate out of perspex (milled it on my homemade CNC) ...the centre of this faceplate mounts onto an 8mm stepper shaft - it was my first attempt & frankly it's not up to scratch. (if I piddle about with the faceplate, I can get the runout is about 0.1mm, but it's somewhat erratic!)
To give you a flavour, here's what a faceplate looks like on someone else's pickup winder (I don't need the slots that his has)...
Here's my perspex one (note my faceplate mounts onto an 8mm stepper motor shaft)....
Ali is obviously the most prefereable material - the face plate need to be at least 3" in diameter (I'll be buying a 3" 4 jaw independent chuck imminently, so 3" is the max I can go) - but how would I go about making a faceplate? I now have a lathe, but not the skills!
I'm thinking here that since the faceplate will ultimately mount onto an 8mm stepper shaft, that a 'donor' 8mm steel rod will feature somewhere in the methodology.
How about something along these lines....
1. Slap a bit of 3" round Ali into a 4 jaw independent chuck....centre it up.
2. Drill an 8mm hole in the centre. (this being the diameter of the stepper shaft it'll mount onto)
3. Turn down the ali to have a 'flange' on the end (say the last 20mm)
4. Part off say the last 50mm.**
5. Put a grub screw into the flange.
6. Insert the aforementioned 8mm steel rod into the part - tighten the grub screw.
7. insert the rod (with part) into the lathe chuck - face off the outer surface of the faceplate.
All being well, the part should now mount onto a stepper shaft & turn 'true' on it's vertical face.
Does this sound plausible? Is there a better/easier way?
**Never having done this.... how the %*$^ do you part off 3" dia Ali?! (the parting tools I've seen for mini lathes all look so feeble with only a small protruding cutting bit!)
You should be able to bore and face in one operation.
Face the plate. Drill the hole to 7 or 7.5mm then ream or bore it to 8.0mm - boring will give you a straight hole at right angles to the face. (if you haven't a boring bar just grind and old drill bit)
Trying to face a 75mm plate mounted on a 8mm bar with a grub-screw sounds like a recipe for failure to me.
Let's say I've a lump of 3" diameter in my chuck - I face it, bore it....how do I part the piece off? Do parting tools for mini lathes handle 3" dia material ok? (or would it just be easier to buy in the right length in the first place!)
PS I like the idea of using an old drill bit as a boring bar - off to Google!
Last edited by HankMcSpank; 08-09-2009 at 09:14 PM.
08-09-2009 #4how do I part the piece off? Do parting tools for mini lathes handle 3" dia material ok?
Your mini lathe hasn't a hope :( Just mark the outside and use a hacksaw
In fact, I'd cut the plate section off prior to turning it.
Try and make it as long as possible even if it's only the boss length.
a 8mm hole doesn't give a lot of support and adding a grubscrew only wants to push it sideways.John S -
Many thanks...John you reinforce a good point there - I'll try & get a bit of aluminium round bar almost as long as the stepper shaft itself - I recall a technique where say the faceplate could be heated & the stepper motor placed in the fridge...if the hole is bored at just the right diameter it should only just coax onto the stepper shaft under this 'thermal difference' condition...as everything returns to room temperature, the faceplate should be held onto the shaft solid. (a bit like wagon wheesl - no not the tuckshop biscuits, but in the wild west - except no fridges or Apaches involved)
What's this method called?
One problem with this is you don't get a second chance, if you do want a 'permanent ' job bore out to get a nice slip fit and then hold the faceplate on with a dab of Loctite retainer. Later if you need it off a bit of heat to the faceplate will break the Loctite.
To get it to run perfectly true make the faceplate slightly longer than the shaft.
Bore the 8mm hole in and put a small counterbore at the front, like your perspex one, now glue the faceplate on, allow to set and put the rear shaft of the stepper in the lathe, support the 8mm hole with a revolting centre and take a clean up pass across the faceplate.
Tape the motor wires to the body whist doing this.
This way it will be as square as you can get it.
.John S -
I did at one stage today spin the stepper as fast as it'll go (about 600RPM) and took a wood chisel to the perspex faceplate surface....the perspex cut like a charm - but obviously the chisel danced about a bit! Now if only I could come up with a way of securing a cutting bit totally perpedicular to the faceplate - I'd not need to piddle about with lathes at all (as it goes, a stanley blade is the perfect width for 'facing' the perspex faceplate - being just slightly longer than the faceplate's radius )
Put a pice of perspex. metal etc in the lathe and face it off, anything doesn't matter as long as it's flat.
Then replace the tool with a piece of square bar [ lathe tool turned over ? ] and offer this up to the faced off disk in the chuck when it touching along it's length tighten the toolpost etc.
Now clamp you stepper with perspex faceplate to the lathe bed with a G clamp on some packing blocks so it's on centre offer it up to the preset lathe tool or bar. Tighen stepper when touching all over.
the stepper is now square to the lathe axis, change the tool round again, run stepper and face off.John S -
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