First, I'd like to thank you guys for the wonderful support you've given so far. I sincerely appreciate that you are helping out with your free time, and your advice has been very valuable for me when working on different projects.
This question might be a little stupid, but I really don't know how to go about attaching a flat disc to the shaft of a stepper motor, as shown below. I want to attach a 12" plastic disc to the shaft of the motor somehow, but I don't know what the proper way is to go about it. Also, I'm not sure what sort of plastic to choose.
In terms of attaching the plastic, I thought I would drill a hole in the center of the disc slightly smaller than the 5mm shaft size so that it would fit tightly on the shaft (shown in the images). I don't know where to go from here, though. The disc will tilt on the shaft when weight is put on it, or it may slide down. Is there a way to really secure it in? (shaft collars maybe?)
Also, I don't know what sort of plastic to use. It needs to be able to be:
bonded to MDF
sawed and drilled without breaking
sturdy and inflexible at thicknesses between about 1/8 and 1/4 inches
I've picked out lots of different plastics to have the sheet be made of: HDPE, PVC, PP, Acetal, and Cast Acrylic. With price in consideration, HDPE is by far the most cost-effective plastic sheet to buy, but I don't think it bonds well. Which type of plastic do you recommend for this application (and where to buy it for a good price?)
You question isn't stupid but when asking a question that pertains to a stepper motor , unless it is strictly a software question, the Standard Operating Procedure on the forum is to post the motor datasheet or a link to a site that has the specs & dimensions for the motor. This is necessary before we even get into your question but I can tell you even without the datasheet that you will need a mounting bit for the disk consisting of two small disks (probably 1" diam) that are compressed by some kind of hardware fitting.
We'll need to see the motor specs to go from there. In the meantime you might want to have a look at this video:
Attach one end of a shaft coupler to the motor shaft.
Insert a threaded rod (cut to length needed) into the other end of the shaft coupler.
Place your plastic circle over the threaded rod with nut and washer on either side of the circle.
Tighten nuts.
Raschemmel, it seems like those "Universal Mounting Hubs" look perfect for what I am trying to do. Although the shaft coupler solution seems to also work, it is more expensive and not as simple as the other solution is. I think I am going to get the UMH, but thanks for the suggestion, LarryD!
BlueIce:
Raschemmel, it seems like those "Universal Mounting Hubs" look perfect for what I am trying to do. Although the shaft coupler solution seems to also work, it is more expensive and not as simple as the other solution is. I think I am going to get the UMH, but thanks for the suggestion, LarryD!
Now on to determining what plastic to use!
go with acrylic. it is harder and less flexible than some of the other pieces. easy to find almost anywhere.
not sure why you want to connect plastic, then MDF. you can connect MDF directly.
I missed the diameter you needed, but if you wanted to play with HDPE, you can go to the dollar store and get a cutting board.
or a dinner plate.
I would very strongly recommend polycarbonate (lexan) rather than acrylic (perspex). Acrylic tends to chip and crack when it it sawed or drilled. Polycarbonate doesn't. It may be a little dearer but it is so much easier to get a good finish. And it really is virtually unbreakable.
raschemmel:
If you told us what the end result is supposed to be it would save time.
All right:
The motor and plastic parts are part of a small rotating table with cans swinging on it, with small blocks of MDF on the top to have the cans swing in. I don't have the CAD file up yet for that, but it should be much clearer what I am trying to do once that is up. I avoided explaining this because it is hard to describe what is going on. :~
Robin2:
I would very strongly recommend polycarbonate (lexan) rather than acrylic (perspex). Acrylic tends to chip and crack when it it sawed or drilled. Polycarbonate doesn't.
Yup, just looked at how to cut acrylic, and that is by bending it till it snaps. Not what I am looking for. Thanks, though!
I have successfully used bullet propeller holders to attach wheels to motors for small robots. Works very well, especially when you add a small rubber washer, or disk on each side of the wheel. It is much cheaper than most other off the shelf options. Here is a link to eBay, but local hobby stores should carry those too:
The heavier the disc, the more motor you will need.
If the disc is only for looks then could it be printed transparency sheet?
You could get an 8" circle out of a 50 cent office store page, maybe they have wider sheets?
You would want a plastic mount on the motor shaft to glue the disk on.
GoForSmoke:
If the disc is only for looks then could it be printed transparency sheet?
You could get an 8" circle out of a 50 cent office store page, maybe they have wider sheets?
You would want a plastic mount on the motor shaft to glue the disk on.
But why not thin sheet metal? Aluminum?
Nope, the disc is not for looks. It will be needed to hold up cans full of items (actual weight), so it must be sturdy.
Also, I'd love to use aluminum, but it is expensive and I do not have access to equipment where I could cut it easily (bandsaw, scrollsaw, etc.) Armed with only a hacksaw, getting the cuts out of the middle will be hard and time-consuming.
BlueIce:
Nope, the disc is not for looks. It will be needed to hold up cans full of items (actual weight), so it must be sturdy.
Also, I'd love to use aluminum, but it is expensive and I do not have access to equipment where I could cut it easily (bandsaw, scrollsaw, etc.) Armed with only a hacksaw, getting the cuts out of the middle will be hard and time-consuming.
Sheet metal cuts clean with a shear or die or EDM. Saw cuts just make me shudder.
I knew guys that did good work on plate aluminum, cutting an arc with a router
Have you ever seen a nibbler? It cuts a sliver of sheet metal at a time at 1000's of rpm.
Sometimes you can find material in thrift shop items. Just keep your eyes open.
What I wonder is how your stepper is up to holding and turning that weight, and stopping it.
Motor at center has the least torque. Motor turning against the edge of the disc has the most.
It could be the inside edge and it would have more angular precision than a centered motor.
The disk is then free to mount on a stronger shaft and the motor won't be bearing weight.
Robin2:
I would very strongly recommend polycarbonate (lexan) rather than acrylic (perspex). Acrylic tends to chip and crack when it it sawed or drilled. Polycarbonate doesn't.
Yup, just looked at how to cut acrylic, and that is by bending it till it snaps. Not what I am looking for. Thanks, though!
I'm a little confused.
I was recommending Polycarbonate. It saws easily with a handsaw or a jigsaw. I cut it with new Bosch T101 wood cutting blades and it gives a nearly clear cut edge.
Sorry, no scrollsaw. If I had one, though, I might go for acrylic.
In my experience Acrylic tends to melt from the heat of the saw blade and can fuse together behind the saw - just a mess.
BlueIce:
Nope, the disc is not for looks. It will be needed to hold up cans full of items (actual weight), so it must be sturdy.
If you're thinking that the weight is going to be carried by the stepper motor, I suggest you check whether your particular stepper motor is designed to support that load. Motors are typically designed to carry radial loads, not axial loads.
