Re: 24Volt DC Unimat Motors
What size and what durometer reading for those o-rings?
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I am currently using Buna N rubber orings. I do have urethane stock to make my own but never got around to making a welding fixture. A project for the future!
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Re: 24Volt DC Unimat Motors
I am currently using Buna N rubber orings. I do have urethane stock to make my own but never got around to making a welding fixture. A project for the future!
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?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
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Re: Do DC permanent magnet motors get old and weak?
Another check is check for short circuit from the windings to the shaft of the armature. Put your ohm or mega meter from the commutator segments to the shaft there should be no reading.
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Re: Do DC permanent magnet motors get old and weak?
Check for carbon packed between commutator? segments or shorted
or open windings, you need a low reading ohm meter for an accurate
check.? Perhaps run it on about 6 volts and load it down and check
for dead or weak spots in the rotation.? Dead spots are usually
open or shorted windings.
On 4/29/24 17:43, vt_biketim wrote:
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Not specifically a Unimat question, but some people here seem to
know a heck of a lot about brushed, DC motors. Do these permanent
magnets get tired after a while? I scavenged one from a lawnmower
labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the
24V battery pack it only gets up to maybe 300 rpm. I replaced the
brushes and made sure the bearings spun nicely and the battery is
fully charged. Am I missing something, or is it junk?
Tim in Vermont
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Re: Do DC permanent magnet motors get old and weak?
Yes, and no, and yes, and so on.
Traditional magnets used in DC motors will lose their magnetism eventually. They can be re-magnetised, and sometimes you can get modern replacements. Modern rare earth magnets - neodymium etc - don't but if they get up to 150° C they lose their magnetism and they don't recover when they cool down. Your lawnmower motor has probably lost its magnetism, and if you tried to get power out of it it would just get very hot. As noted if you wanted full power it would take a lot of current, but a couple of car batteries would be up to the job. With the motor idling it shouldn't draw more then an amp or so, and you should easily get full speed.?
At any rate I would say the motor has had it, and probably not worth attempting to fix it.
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Re: Do DC permanent magnet motors get old and weak?
Good points, Bill. The Neuton mower was a simple arrangement of battery pack, switch/relay board, and motor. After removing the pieces from the mower carcass I simply charged up the battery pack and touched the leads to the terminals. All original wiring and the original battery, just bypassed the switch and relay. I do think the reason for taking it out of service was a slow output speed.
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Re: Do DC permanent magnet motors get old and weak?
Hi Tim if it has ceramic magnets they will loose their strength due to heat. If you find the motor runs hot in a short period of time they have possibly lost their magnetism. You might be able to find a magnito zapper to re energise them. I have one but I'm in Brisbane Australia.
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Re: Do DC permanent magnet motors get old and weak?
Is your battery capable of providing 500 watts of power? Is your wiring capable of carrying nearly 21amps of current. That's what you're asking your power supply for.?
I have one or two supplies that can handle that much power, and a bunch that cannot. If the supply is rated for 24vdc, at 500 watts, it should have a bit over 20833ma or nearly 21 amps of current available.? If if it does, check your wiring and connections. Should be a minimum 12 AWG wire, per this calculator:? https://www.calctool.org/electronics/24v-wire-size
Bill in OKC?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Monday, April 29, 2024 at 06:43:04 PM CDT, vt_biketim <tchock59@...> wrote:
Not specifically a Unimat question, but some people here seem to know a heck of a lot about brushed, DC motors. Do these permanent magnets get tired after a while? I scavenged one from a lawnmower labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the 24V battery pack it only gets up to maybe 300 rpm. I replaced the brushes and made sure the bearings spun nicely and the battery is fully charged. Am I missing something, or is it junk?
Tim in Vermont
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Re: Do DC permanent magnet motors get old and weak?
In the model railroading world, permanent magnet DC motors definitely have problems with magnets weakening.? The result is that the motor loses power runs hotter.
Some have put in new magnets which are often a stack of smaller magnets since it's hard to find a solid one-piece magnet the correct size.
This is a typical in the older open frame motors that look like this.:
And this is one where a number of small magnets have replaced the one large one which probably got weak.
Charles E. "Chuck" Kinzer
On Monday, April 29, 2024 at 04:43:05 PM PDT, vt_biketim <tchock59@...> wrote:
Not specifically a Unimat question, but some people here seem to know a heck of a lot about brushed, DC motors. Do these permanent magnets get tired after a while? I scavenged one from a lawnmower labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the 24V battery pack it only gets up to maybe 300 rpm. I replaced the brushes and made sure the bearings spun nicely and the battery is fully charged. Am I missing something, or is it junk?
Tim in Vermont
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Re: Do DC permanent magnet motors get old and weak?
DC motors wear out. Think of car starters and even back further to car generators. They had to be periodically taken apart and the armature turned down and new brushes installed. Most of the new motors are throw aways, can not be rebuilt or if you can get them apart, no parts available.
?Jeff
On Monday, April 29, 2024 at 07:59:20 PM EDT, John Dammeyer <johnd@...> wrote:
Hi Tim, I’m not sure it applies to older DC motors but I do know that you can’t take a stepper motor apart without damaging the magnetic field.? The structure around the armature serves as a ‘keeper’ for the magnet.? Remember the old horsehoe magnets also required a small bar across the end when the magnet was stored. So it’s quite possible on a newer lawnmower DC motor that the motor is designed to not be taken apart. John ?
From: [email protected] [mailto:[email protected]] On Behalf Of vt_biketim
Sent: April 29, 2024 4:43 PM
To: [email protected]
Subject: [Unimat] Do DC permanent magnet motors get old and weak? ? Not specifically a Unimat question, but some people here seem to know a heck of a lot about brushed, DC motors. Do these permanent magnets get tired after a while? I scavenged one from a lawnmower labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the 24V battery pack it only gets up to maybe 300 rpm. I replaced the brushes and made sure the bearings spun nicely and the battery is fully charged. Am I missing something, or is it junk?
Tim in Vermont
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Re: Do DC permanent magnet motors get old and weak?
Hi Tim, I’m not sure it applies to older DC motors but I do know that you can’t take a stepper motor apart without damaging the magnetic field.? The structure around the armature serves as a ‘keeper’ for the magnet.? Remember the old horsehoe magnets also required a small bar across the end when the magnet was stored. So it’s quite possible on a newer lawnmower DC motor that the motor is designed to not be taken apart. John ?
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From: [email protected] [mailto:[email protected]] On Behalf Of vt_biketim
Sent: April 29, 2024 4:43 PM
To: [email protected]
Subject: [Unimat] Do DC permanent magnet motors get old and weak?? Not specifically a Unimat question, but some people here seem to know a heck of a lot about brushed, DC motors. Do these permanent magnets get tired after a while? I scavenged one from a lawnmower labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the 24V battery pack it only gets up to maybe 300 rpm. I replaced the brushes and made sure the bearings spun nicely and the battery is fully charged. Am I missing something, or is it junk?
Tim in Vermont
|
Do DC permanent magnet motors get old and weak?
Not specifically a Unimat question, but some people here seem to know a heck of a lot about brushed, DC motors. Do these permanent magnets get tired after a while? I scavenged one from a lawnmower labeled 24VDC/500 W/4300 rpm. When I hook it up directly to the 24V battery pack it only gets up to maybe 300 rpm. I replaced the brushes and made sure the bearings spun nicely and the battery is fully charged. Am I missing something, or is it junk?
Tim in Vermont
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Re: iGaging Digital 6” Digital with remote
I'll assume you bought the newer model; I have the previous generation on my mill/drill (x,y,z), and I've used two others for similar projects.
The weak point in the earlier ones were the connectors.? They worked fine if the cords never moved, but the metal cages tend to spread; the Y axis on the mill was flakey for a few years, crimping the connector gently helped a great deal.? Anything you do to anchor the cable before it gets to the display will help.? Yours should have the DC adapter option, if so use one.? The batteries in the older units die pretty fast because they never actually turn off, it's just the display that turns off.?It seems like every time I use it, I have to replace a battery somewhere.? The nice thing about the magnetic scale is that you can cut them to length, which makes installations look much better.
I have an extra, newer one I was going to add to my Unimat, but have never got around to it.
-Dave
On Wednesday, April 24, 2024 at 06:39:17 PM PDT, OldToolmaker via groups.io <old_toolmaker@...> wrote:
I just purchased an igaging 6” digital read out with remote display. I am going to mount this on my Unimat DB200 to measure linear travel. If this works well I will also mount another readout to measure cross travel.
If anyone has implemented something similar I would appreciate hearing about your experience and any advice.
Dick
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Re: iGaging Digital 6” Digital with remote
I have one of those sitting right in front of my Unimat. Had it forever… and haven’t installed it. I’ll be watching.?
I bought it for a mini mill installation that never happened.?
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Re: iGaging Digital 6” Digital with remote
Would that be something like ?
?
Op 25-04-2024 03:39 CEST schreef OldToolmaker via groups.io <old_toolmaker@...>:
?
?
I just purchased an igaging 6” digital read out with remote display. I am going to mount this on my Unimat DB200 to measure linear travel. If this works well I will also mount another readout to measure cross travel.
If anyone has implemented something similar I would appreciate hearing about your experience and any advice.
Dick
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forum/?OFF-SET-tailstock-center-65965#post105972
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?SMALL QC TOOL POST PLANS?
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Re: iGaging Digital 6” Digital with remote
Measuring the linear travel would solve a lot of my fiddling with the metric calibration...? following conversation.
Tamra
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iGaging Digital 6” Digital with remote
I just purchased an igaging 6” digital read out with remote display. I am going to mount this on my Unimat DB200 to measure linear travel. If this works well I will also mount another readout to measure cross travel.
If anyone has implemented something similar I would appreciate hearing about your experience and any advice.
Dick
--
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?SMALL QC TOOL POST PLANS?
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Re: For sale in Austria: EMCO UNIMAT 3 with many acccessories incl. original EMCO cabinet
Everything sold by Niels is priced at ungodly levels. I think he only dabbled in business as a pass-time
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You could say so - Niels Brijlandt sold his set for some �4,5K wheres Vilen (the present seller in Austria) sells for just 1,1K. That too is a lot of money - but just 25% of what Niels charged.
Op 23-04-2024 14:14 CEST schreef Tamra <tamrabrogdon@...>:
?
?
I do think this one is less expensive the one posted in the Niel's photos... but that is purely from memory, that I have the price and seller in my head properly.
I keep forgetting to play the lottery, so I'm trying to keep lathe acquisition disease in a sleeping state.
Tamra
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Re: For sale in Austria: EMCO UNIMAT 3 with many acccessories incl. original EMCO cabinet
You could say so - Niels Brijlandt sold his set for some �4,5K wheres Vilen (the present seller in Austria) sells for just 1,1K. That too is a lot of money - but just 25% of what Niels charged.
Op 23-04-2024 14:14 CEST schreef Tamra <tamrabrogdon@...>:
?
?
I do think this one is less expensive the one posted in the Niel's photos... but that is purely from memory, that I have the price and seller in my head properly.
I keep forgetting to play the lottery, so I'm trying to keep lathe acquisition disease in a sleeping state.
Tamra
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Re: New Mr Pete Unimat video up
P.S. I definitely will make some more screws of 260 brass that is a very useful video.
Tamra
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OldToolmaker
Bill in OKC too
Herman de Leeuw
Tamra