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Old 4th January 2009, 05:57 PM   #51
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"Any progress?"

I got my Delta bench drill press out of storage (150 lbs) and moved here, along with an Enco milling table add-on (65 lbs) and an Enco rotary indexing table (26 lbs). Add another few hundred pounds of bolts, motors, transformers, toroid cores, and assorted scrap metal stuff that might be useful. I'll be using the drill and add-ons to mill the teflon and some aluminum supports. I've got a real Enco Mill-drill in storage, but at 750 lbs, that was out of the question for hauling back in the car. The add-on milling table:

http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

I recently ordered a tool stand from Harbor Freight to put it all on and it arrived made out of paper thin sheet metal (even though its rated for 500 lbs!). I'm ordering a second one to double up the parts for a safe stand to put the drill press and milling table, etc on. Next time I'll pay the higher price at Enco for a real stand, I shoulda known better.

Got most of my teflon and aluminum material in. I already have some nice big stepper motors but I just found a nice micro-stepping controller for them recently, which I bought two of. I want to test them out with the steppers first before I recommend them though, sometimes current limiting power resistors are needed too.

http://www.mpja.com/prodinfo.asp?number=17451+MS

The micro-stepping controller isn't really needed for the belt drive motor, but may be useful for the toroid positioning motor, where more angle resolution is required for progressive winding.

I've located sources for 5 mm pitch timing belts and sprockets, these can be cut to most any custom width and the sprockets are available in various widths including custom. Belts lengths are available in various standard lengths, but length cannot be custom varied. Some belt tightening mechanism is required in the design.

I still have to order these items, but I prefer to actually construct the teflon and aluminum assembly first to measure the best belt length more accurately. Some milled slots in the aluminum side plate for sliding stepper mounting bolts will suffice for belt tightening.

I may use a tensioned timing belt to rotate the core against rubber rollers too, one of several design options here. The belt can even have some teeth filed down to compensate for the change of toroid radius with the windings going on, to keep constant stepper to toroid angles for precision progressive winding.

OT:
Hauling really heavy loads of stuff in the car is getting more dangerous than ever, as I found out on the trip back. I was minding my own business when I saw a pickup truck and an SUV on RT 81 having a passing battle with each other, coming up from behind. I was thinking right away: here comes trouble. Then they pulled right in front of me, honking at each other, and I immediately thought "insurance scammers!". I was already half way into an evasive manuever into the next lane when they slammed on the brakes. I went sailing by them fortunately. They probably picked on me because the car looked like it was bottomed out from all the weight. Thank goodness I wasn't hauling the 750 lb milling machine in the back seat.

Don
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Old 4th January 2009, 06:41 PM   #52
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Very astute, Don. You probably saved your life with your observance of the insurance scammers. That drill press could have killed you if you had to slam on the brakes.

Well done with the progress on this & a great 2009 to you!
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Old 4th January 2009, 07:14 PM   #53
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I had an Enco Mill but it was just to heavy to deal with. I am so glad i didn't buy a real Bridgeport at 2,000lbs! I ended up selling my mill and now i am looking at the smaller table top sherline/Taig models. All i really want to do is machine faceplates and small parts. this way i can get a small lathe too and even the small ones will machine knobs and bearings and what not.

Only problem with the mini stuff is the tooling is MORE expensive!



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Old 4th January 2009, 08:34 PM   #54
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"Well done with the progress on this & a great 2009 to you!"

Thankyou jkeny! I'm just hoping that I can get going on the machining before too long. (ie, Spring.... kayaking, hiking.... )
Machining stuff is such a tedium though. And messy.

"I had an Enco Mill but it was just too heavy to deal with. I am so glad i didn't buy a real Bridgeport at 2,000lbs! I ended up selling my mill and now i am looking at the smaller table top sherline/Taig models. "

Yeah, I know, the Enco mill-drills looks so cute in the ads, but are incredibly heavy (750 lbs + 150 lbs for the stand, and maybe another 100 lbs for a rotary table) on close encounter. At least it uses the standard cutting bits and accessories. One thing I found when I put mine in storage was that it can be split up into 3 or 4 150 to 200 lb parts. I made some wood boxes with handles for each part. Not too bad to cart them around on two wheel dollies then.

Bridgeport.... that would fall thru my floor.

I've recently seen this interesting half size mill-drill at Harbor Freight (325 lbs):

http://www.harborfreight.com/cpi/cta...unction=Search
(item # 93885)

Claims to have a standard R-8 spindle too.

But its still nearly the same price as the bigger Encos. $1000, and I am wary to say the least of anything from Harbor Freight. The quality there is totally all over the map. I would check one up close at a dealer first, definately.

They also have some smaller mini-mills at around 100 lbs to 150 lbs (and $300 or $400) that look similar (models 47158 and 44991), but on closer inspection of their manual, they don't have a sliding quill for the drill chuck. They move the entire head assembly, including motor, up and down to drill anything. This would be undesireable to me for making incremental milling depth adjustments.

It also appears that made in Taiwan machinery is generally better made, although more expensive than the Chinese stuff. I'm sure the Harbor Freight stuff is from China. But with the $1000 price on the half size model, maybe its a Taiwan model?

Some other interesting models at H-F:

model 97208 4 inch rotary table for $90

gotta see this one, a real OMG moment:
models 66051 and 66052 CNC hobby mills!!!! but $3000 to $5000 (but gee, if they can make a CNC mill for $3000, how come the toroid winders are $24,000)

Enco is mostly bigger stuff.

Don
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Old 18th March 2009, 03:27 PM   #55
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I'm still watching this thread for activity with great interest. I have access to a well equipped machine shop and am interested in the latest developments. I even have a little time to spare to make one.

I'm also building a CNC machine that would be able to mill out aluminum and Teflon parts...

Thank you for the time you've invested so far!
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Old 18th March 2009, 03:54 PM   #56
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Quote:
Originally posted by jkeny
Very astute, Don. You probably saved your life with your observance of the insurance scammers. That drill press could have killed you if you had to slam on the brakes.

Well done with the progress on this & a great 2009 to you!
That's why we carry guns in our cars in SoCal. Endanger MY life willya!
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Old 18th March 2009, 06:15 PM   #57
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The microstepping motor I wanted for toroid positioning (it goes with the previously mentioned microstepping controller above, same manufacturer) has been out of stock for a while. Supposed to be back in stock in 3 months:

http://www.mpja.com/prodinfo.asp?number=17455+MS

But I recently figured out that this other one is also rated for microstepping. (has to have a sinusoidal waveform from its pole shapes):

http://www.mpja.com/prodinfo.asp?number=17748+MS

So I just ordered 4 of them to try out. Will likely arrive end of this week or early next.

I decided that my original toroid positioning scheme using a timing belt needed modification. I was going to use one stepper with a long belt pulling the toroid up against two rollers near the winder mechanism. But it became apparent that the belt has to be routed around a lot of stuff there, including the other stepper for the wire drive and the slack wire accumulator spring tensioner. This would require a bunch of belt idlers to steer it around them.

So now I am pursuing a design where the toroid positioning belt is double C shaped, just like the wire drive belt. The belt wraps around most of the toroid then does a 180 around two stepper drive pulleys near the winder. The belt then routes back around the toroid (but at larger radius, no rubbing). Two more steppers are positioned near the max width points of the toroid to route the outer belt sections safely and they also push against the inner belt and toroid, providing centering constraints. These two steppers are spring loaded against the toroid, and so accomodate various size toroid cores. Finally a 5th pulley is arranged at the far back of the toroid (not rubbing the inner belt) to tension the outer belt section and is mounted on an optical encoder shaft. It's spring tensioned, maybe 9 inches away from the back of the toriod, so the outer belt section has clearance from the inner belt section.
The four positioning steppers are run in parallel from the same microstepping controller.

I purchased all the belts and pulleys from here:

http://www.sdp-si.com/web/html/viewcat.htm

Mostly from the inch drive components catalog. They're pretty pricey though. About $12 per sprocket, $21 per belt. I priced out what it would take to make some idler shafts with ball bearing mounts and they came to around$100 each. That's when I decided that multiple $10 stepper motors were a much better way to go. Although, one could machine off the stepper rotor poles to make a ball bearing idler shaft I guess.

I suppose, if one used enough spring loaded steppers around the toroid, with rubber rollers, that the toroid belt could be dispensed with. That seems to be how the commercial design is configured. They must have some computer algorithm to figure out the toroid angle, since its radius changes (dynamically) as its being wound. Good accuracy of toroid angle is necessary for progressive winding.

My plan is to adhesively bind a thin rubber sheet (maybe serrated sections) to the back side (non toothed) of the toroid timing belt, of similar width to the wire layer being wound. This spacer layer ends at the C belt gap where wire is being wound on. This way, the belt runs at constant radius during the winding operation. (the wire layer taking the place of the rubber spacer during rotation) A bit of a pain to configure drive belts though. Probably have to have a collection of preconfigured drive belts handy.

One concern yet, is the phasing between the multiple steppers during a layer wind. Some inaccuracy is bound to creep in with the toroid radius (and spring loading) affecting the belt length between stepper sprockets. There are rubber flex couplings available for allowing a little flex of the belt sprockets. I'm hoping I can skip that (they're expensive as H), maybe just not tighten the belt so much. At this point, I will depend on the optical encoder for feedback of belt position. I will just have to experiment on this. (the optical encoder I picked up surplus some time ago, but probably are similar available on Epay. I'm using a 1000 count encoder, and the belt sprocketing is arranged for 2 micro steps per optical count)

Don

I also have another hot project going on, modifying a Tek 576 curve tracer for tube tracing. Slow progress on the winder.
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Old 22nd April 2009, 01:40 AM   #58
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Hi all,

I've been studying the drawings and find the concept brilliantly simple!

Has anyone fabricated this device?

Would any DIYers be interested in investing in one? I'm giving serious thought to making a few.

My version would have a reduction/motor to drive the belt and the toroid's ring and pinion.

Just brilliant...
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