Hey Iggy - stepper motors ?

snipped-for-privacy@snyder.on.ca fired this volley in


The original post never smelled of CNC, or I'd not have suggested that a wiper motor could be "servo'd".
For the sort of app he seemed to be asking for, the "feedback" could be a simple as a limit switch. As I wrote earlier, "feedback" covers a lot of ground.
Lloyd
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snipped-for-privacy@snyder.on.ca prodded the keyboard

I wouldn't say CNC. Certainly the wiper motor stops dead when the power is removed, well maybe not the armature, but the table does. I can cut a slot within a tenth of a given distance. A caveat is to take the backlash out before cutting or you end up cutting short.
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wrote:

Cutting short isn't as bad as cutting long!! You know the old saw - "I cut it again and it's STILL too short"
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On Wed, 28 Jan 2015 22:58:41 -0600, Terry Coombs wrote:

Having worked with stepper motors in space- and power-constrained devices, I am highly prejudiced against them. That doesn't mean they won't work -- it just means that I've had bad experiences. I much prefer a servo motor driven by a feedback loop (at least, when I get to design the controller).
Check with Herbach & Rademan (http://www.herbach.com ) for motors. They may not have what you want, but they have lots of stuff in that sort of size.
For pulleys and belts and whatnot, check Stock Drive products. They aren't a surplus place, but they have fair to middlin' prices on fair to middlin' stuff, and they'll have the same thing next year. I've had good success tossing together mechanisms using their parts.
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Tim Wescott
Wescott Design Services
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Tim Wescott wrote:

Thanks , I'll check that supplier for motors . As far as gears and pulleys , I'm equipped to make those , from casting the blank in aluminum or brass to final machining . I have lots more time than money ... and a big pile of casting stock .
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On 29/01/15 18:18, Terry Coombs wrote:

Do you heat treat the aluminium at all as my limited experience with as cast items is it is soft and gummy and not nice to machine. A mate that worked as a designer at a company the made a number of products with aluminium castings said they always heat treated them, not for strength reasons, but for machinability as the surface finish achieved was much better and some other benefits.
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David Billington wrote:

My experience has been that extruded stock makes gummy castings . Material that was originally cast usually machines just fine . My usual practice is to dunk the casting in water as soon as it comes out of the mold , this both helps machineability and helps get residual molding sand off the piece . Letting a casting stand for a few days also helps , as I understand it aluminum gets some temper from just aging .
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On 29/01/15 22:17, Terry Coombs wrote:

Sounds like you are doing a basic post cast heat treatment with that procedure. The castings I've had done were done commercially with a standard casting alloy, LM25?, and were soft and not nice to machine.
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wrote:

It really all depends on what your smelting stock is. What alloy are you casting? If you start with 6061, you will get a machineable, weldable casting. If you start with 3000 series aluminum, you will get bubblegum. 6061 age hardens.
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snipped-for-privacy@snyder.on.ca wrote:

So does A356 - as do most aluminum alloys to some degree . That soft/stretchiness of the 3000 series is one of the attributes desired for stamping and other cold forming ops isn't it ?
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wrote:

From $12.99 w/ f/s on eBay http://tinyurl.com/of8584m How much torque do you need?

Cogs are cheap as dirt online.

David's link looks like a promising start.
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Larry Jaques wrote:

Those cheaper ones are all nema 17's , I already have 2 of those . I have the power supply here now that I intended to power those with , I'll be looking at some reduction for torque increase . I can get either 9:1 or 16:1 in a fairly small package using 20dp gears . I never expected the responses this thread generated ... I just wanted a uniform speed for the X , and if I can work it out the Z .
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wrote:

With steppers on x and y you can program for angle cuts too.
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wrote:

It's my impression that for the DIYer, stepper controls are easier and cheaper to source - but if good surplus servo controls are available at reasonable price, of coarse use them. I've got several rather large and clunky servos around, but no drive circuitry. Definitely too big to put on my Myford lathe - - - - . Then there are the servoed motors out of inkjet computers - too small for the job. Steppers out of old LaserJets are a dime a dozen and about the right size.....

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On 2/1/2015 3:25 PM, snipped-for-privacy@snyder.on.ca wrote:

Coffee can (2 pound) sized servo's are used on CNC CAD/CAM plasma tables. Might find one for sell and have two X/Y nice ones with internal glass. Mine does - and has a third smaller one for Z. So I can cut wavy sheet metal following he metal up and down while cutting.
Martin
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wrote:

I noticed that a minute after sending the URL. Vendors put "NEMA 17 23 34" in the titles and it screws up searches. I saw one listing for a boresnake which stated that it worked on bores from .17 to 12ga. ;)

Also, don't forget Burden Surplus www.surpluscenter.com for all sorts of gearhead drives at different RPMs for cheap prices.
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On Sun, 01 Feb 2015 05:59:21 -0800, Larry Jaques

I've got a couple Nema 23s I have considered putting on the Myford.
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