Author Topic: Holder for proxon spindle motor for lathe  (Read 1153 times)

Offline PekkaNF

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Holder for proxon spindle motor for lathe
« on: June 09, 2017, 05:05:03 PM »
This sort of stuff. Standard 43 mm attachement ring.

Had some trouble reaching all the features - now I know how to desgin it easier to make. Big thing would have been to bolt the "ring" from outside, it was a proverbial to make couterbores (recesses?) to M4 hex cap bolts.

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #1 on: June 10, 2017, 04:53:40 AM »
Soaked 16x16 mm hot rolled in vinegar overnight to remove scale, it came out with paper towel.

Then I used surface plate and try square to mark centre line and drilled holes for bolts and threads.

This is the easy part, more difficult it is to deside how to clamp down the aluminium cast spindle motor into aluminium bracket.

Need a plastic part not to deform he spidle aluminium cast housing that has bearing in it. Aluminium gets grabby.

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #2 on: June 10, 2017, 07:25:03 AM »
While on other business on the shops I found pipe clamp that looks promissing, 57 mm ominal diameter. it would be easy to turn a shallow 1,5 mm groove on donugh perimeter for the U-bolt, but the sheet metal part would need modification, or it would need a replacement. Doable, but more complication and sticking parts out.

So, I'm thinkking of slitting the top and tapping a place for a pinch bolt.

Change on gardening and a wellcome break on moving dirt and stuff with wheelbarrow.

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #3 on: June 10, 2017, 09:00:34 AM »
So slit and pinch bolt: Mental note next time find bigger bar if you are planning of using this construction.

Good news is that all bolts were M4. Bad news was that it took some planning and drawing to get it to right location. It does not look like, but just 2 mm any way and something would have gone trough inner hole. Fiddly but it works.

The ring closed just a little, I could feel machingin cogging when pushed it in and just a little nip tightened it solid.

Rest of the eveneing gardening and maybe setup that this was for follows tomorrow.

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #4 on: June 11, 2017, 03:27:43 PM »
So, here is my contraption nearly ready to true resin bonded diamond wheel.

Anybody trued and/or opened up resin bonded diamond wheel? Any advice to spare?

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #5 on: June 12, 2017, 03:34:40 PM »
Bit of a progress. Desided to split the off hand grider mounting plate ja truing brake guide in half. Gives a bit more adjustment and flexibility.

Two things left, more demanding part is the brake stopper. I have an idea as shown on the picture, but can't decide if that should just a detachable hard stop or does the alumimium extrusion sled (where the truing brake is) some sort of spring to press against this stop or is hand pressure good enough.

Any advice?

pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #6 on: June 13, 2017, 04:52:41 PM »
Nearly ready for it's first task. The extrusion should stay put in the groove. Bolted down 12 mm ground rods from both ends. Other one is pinched down to sledge (big extrusion on the middle) and is pushed with adjustment screw. it works. Least now.

Looks particulary ugly on the pictures, should have vacumed and used petty lense on the camera.

Pekka

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #7 on: June 14, 2017, 04:01:31 PM »
Used nearly one hour to fit gas strut into it. The gas strut pushes the sledge agains adjustment screw. Works pretty well.

First surprice was that mounted point was out of round nearly 0,5 mm. But it got straigth in no time.

The "brake wheel" wears out quickly, went from 25 mm OD to 20 mm. Diamond disc lost almost nothing, but wobble died off almost completely, now it looks straight when it is running, alhough i can still hear that it is not true 100%, but close enough. It is not balanced, so probably it is now close enough.

have to buy a stick to open it

Pekka

Offline DICKEYBIRD

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Re: Holder for proxon spindle motor for lathe
« Reply #8 on: June 14, 2017, 07:01:28 PM »
Very interesting, thanks for posting.  Looks good!

I'm faced with a similar chore.  I cobbled up a T/P grinder for my lathe with a 4" CBN wheel.  It's a Chinese wheel that has runout that can't all be adjusted out at the hub.  I found a few silicone carbide wheels on ebay that will hopefully true it up.
Milton in Tennesee

"Accuracy is the sum total of your compensating mistakes."

Offline PekkaNF

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Re: Holder for proxon spindle motor for lathe
« Reply #9 on: June 15, 2017, 02:16:22 AM »
I only google resin bonded diamond wheel truing with silicon carbide wheel.

Most of sources had something in common, like using a brake or motor and make that truing wheel run delibrately slower than ir would if free running. I did not find much information about the grit of the truing wheel or grade, don't know how much it is of consequence.

One friend just used standard SIC wheel on small pedestal grinder on MDF board, flicked the switch on and off and brought it contact with diamond cup wheel and said that cup wheel got straight, but not necessary true, because of the manual (lack of) control. Said that it did not need "opening" after it, worked just fine.

Looks like front bearing of that Proxon spindle is finally shot, It is old and "lubricated for life" bearings generally don't last lifetime. Also can't judge if the front bearing has ZZ on small friction steel/elastic seal, probably something to consider when I order bearings for it.

I should give a call to local tool shop if they have opening sticks for diamond wheels.

I would like to hear other experiences, mine comes from forums and two tries. Not much of an experience.

Pekka