Mark Norfleet Posted November 16, 2020 Report Share Posted November 16, 2020 52 minutes ago, Don Noon said: The marginal result is that I'm using a VFD advertised as "1HP" and using only 1 phase of the 3 to run a 1HP single-plase dust collector. Yup, and I suspect that is torturing your motor. It's a matter of degrees... Time will tell... 3 phase VFDs and variable DC drives work fine at speeds well below 50% of rated motor speed. But there's always the cooling issue, which can be mitigated with a separate fan. There are so called VFD rated motors built with more insulation than has been used in the past, but they're expensive. That said, many have used VFDs on older motors for decades without incident. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted November 16, 2020 Author Report Share Posted November 16, 2020 I'm so pleased with where this thread has gone! We've covered some really interesting ground here. Thanks again to all who have shared. Hopefully this thread will be of benefit to folks in the future, as well. I've certainly learned a lot. Quote Link to comment Share on other sites More sharing options...
Don Noon Posted November 16, 2020 Report Share Posted November 16, 2020 28 minutes ago, Mark Norfleet said: Yup, and I suspect that is torturing your motor. It's a matter of degrees... Time will tell... I am not worried at all about the motor in my particular case, as running a dust collector at half speed will reduce the motor torque load by about a factor of 4. And the motor is TEFC, where I modified the fan cooling system to move more air. Again, the biggest concern is avoiding keeping the start-up capacitor from melting by making sure it is not constantly energized. For other applications where the torque load remains about the same at low speed, there would be more of a concern about the motor overheating. For my bandsaws, retrofit with PM DC motors, the motors are robust (heavy) industrial Baldor motors, and so far I have never noticed the motors getting more than barely above room temperature. I don't run them as slow speed for heavy cuts, though. Just another anecdote that may be of interest for motorheads... I got a 3/4 HP Baldor PM DC motor for my lathe off of eBay, which looked immaculate. However, when I got it, it was frozen. The overheat indicator was red, not green, and upon disassembly, I found that all of the rotor potting had been fried and flaked off. I got my money back on the deal. But, surprisingly, the motor windings were not shorted. After cleaning out, re-balancing, and truing up the commutator, it works fine on my lathe. Some voltage/speed measurements indicate that the magnets were partially demagnetized by the heat, but not a big deal for what I need. On that application, I haven't bothered to get a controller, but just use a Variac, rectifier, and smoothing capacitor to supply DC power. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted November 19, 2020 Author Report Share Posted November 19, 2020 1/2 horse 90 volt Vevor PM DC motor, KMBD variable speed control. Took me all of 20 minutes to wire. At top speed, no more than 50db at two feet. Looking forward to getting a wheel on there. VID_20201119_141553.mp4 Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 11, 2020 Author Report Share Posted December 11, 2020 6x1.5" 180 grit CBN wheel from Woodturners Wonders. Mounted the whole thing on a melamine board with handles for getting into and out of storage in my small shop. Awaiting the appropriately sized tool rest table from veritas (their jig comes stock with a table for a 1" wheel) and it'll all be finished. Did some freehand grinding on an HSS narex marking knife, thing really moves metal quick and cool. Hard to imagine how aggressive the 60 grit wheel must be. Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted December 11, 2020 Report Share Posted December 11, 2020 Very nice job, Jackson. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 11, 2020 Author Report Share Posted December 11, 2020 44 minutes ago, Michael_Molnar said: Very nice job, Jackson. Thank you, Michael. I'll make another report when the tool rest is installed and I've had the opportunity to grind several kinds of blade Quote Link to comment Share on other sites More sharing options...
Mark Norfleet Posted December 11, 2020 Report Share Posted December 11, 2020 That looks good Jackson! I do hope there's some conduit in it's future though. How is the concentricity of the wheel and what did you use as a mount on the motor shaft? I'll be interested to know if you think the motor has enough horsepower once you've got the rest installed and have used it a fair bit. Enjoy! Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 11, 2020 Author Report Share Posted December 11, 2020 4 minutes ago, Mark Norfleet said: That looks good Jackson! I do hope there's some conduit in it's future though. How is the concentricity of the wheel and what did you use as a mount on the motor shaft? I'll be interested to know if you think the motor has enough horsepower once you've got the rest installed and have used it a fair bit. Enjoy! Thank you, Mark. Yes, I intend to redo the wiring entirely, heat shrink it, and route it out of the way. The concentricity of the wheel is excellent, made easy to ensure by the mated pair of hemispherical washers included that prevents the slight skew of the nut on the threads from introducing runout. It runs extremely quiet, which I especially enjoy. The shaft of the motor is 5/8 and unthreaded, but the arbor of the wheel is 1/2. I was obliged to pick up the threaded arbor from McMaster Carr in order to mount the wheel. Quote Link to comment Share on other sites More sharing options...
violguy Posted December 12, 2020 Report Share Posted December 12, 2020 (edited) On 11/13/2020 at 12:40 AM, Violadamore said: I just don't understand you guys fascination with things that spin fast. All I use my bench grinder for are drill bits, metalworking tools, and stock removal. Everything else goes to stones and plates. It's just a guy thing! Edited December 12, 2020 by violguy miss-spelled word Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 12, 2020 Author Report Share Posted December 12, 2020 I'm more interested in running slow and cool, hence the drive unit. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 13, 2020 Author Report Share Posted December 13, 2020 Now with tool rest! Finally complete. So far I have ground a couple of chisels and some knives, various compositions of high speed or tool steels. Even at full tilt, the chunky aluminum wheel absorbs so much of the friction heat that I can grind at a leisurely pace right up to the edge and not fear burn. The 180 grit wheel leaves a toothed edge that will shave hair, but I still go to 1k, 3k, and 10k water stones after for a far superior hone. Best tool I've built so far. Quote Link to comment Share on other sites More sharing options...
David Burgess Posted December 13, 2020 Report Share Posted December 13, 2020 Very nice. What is the source for the tool rest? Can it be ordered directly from Veritas? It looks like that could be useful on many setups. Any idea how the CBN coating on the wheel holds up over time? (My diamond plates started to get dull pretty quickly) Quote Link to comment Share on other sites More sharing options...
Don Noon Posted December 13, 2020 Report Share Posted December 13, 2020 Yes, that's the same Veritas toolrest I have for my bench grinder. You can get it from Lee Valley. Nice work Jackson; just the conduit left to go. Waaaaay overkill on the motor size, but why not. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 13, 2020 Author Report Share Posted December 13, 2020 5 hours ago, David Burgess said: Very nice. What is the source for the tool rest? Can it be ordered directly from Veritas? It looks like that could be useful on many setups. Any idea how the CBN coating on the wheel holds up over time? (My diamond plates started to get dull pretty quickly) Don is correct, you can order it from veritas. The grinding jig for chisels, plane irons, etc is an add on unless you buy their "basic grinding set" which includes the tool rest with slot for 1" wheel. If you have a wider wheel, they make you buy it separately. So I have the original just sitting around for now. So far I have not been disappointed with any veritas products. I have two of their planes, some bench hardware, a tapering gauge (perfect for calibrating drill press/depth punch), marking gauge, and a few other things. My hat is off to our Canadian neighbors. As to the CBN wheel, Woodturners Wonders guarantees it for life. We'll see what that means in the real world with time. I can firmly recommend this setup, but agree with Don about the overkill. The same outfit sells a 1/4 hp motor, which would have been the way to go if I had understood what I do now. At some point I may rebuild it with that motor and convert my drill press to DC with this one. Quote Link to comment Share on other sites More sharing options...
Don Noon Posted December 13, 2020 Report Share Posted December 13, 2020 37 minutes ago, JacksonMaberry said: I can firmly recommend this setup, but agree with Don about the overkill. The same outfit sells a 1/4 hp motor, which would have been the way to go if I had understood what I do now. At some point I may rebuild it with that motor and convert my drill press to DC with this one. 1/2HP DC permanent magnet motor would be overkill for a drillpress too. You could use it (as I do) on a small bandsaw. As I probably mentioned, for these applications that are only used for intermittent loads, the limiting factor (for PM DC motors) is the power supply. With a given (usualy 12 amps or less) supply, performance of 1/4, 1/2, or 1 HP motors won't vary significantly (as long as the nameplate RPM is the same). Only if you want to use them at high load continuously will the difference show up in heat handling capacity. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 13, 2020 Author Report Share Posted December 13, 2020 Thanks as always, Don! Quote Link to comment Share on other sites More sharing options...
Jeff White Posted December 13, 2020 Report Share Posted December 13, 2020 2 hours ago, JacksonMaberry said: Don is correct, you can order it from veritas. The grinding jig for chisels, plane irons, etc is an add on unless you buy their "basic grinding set" which includes the tool rest with slot for 1" wheel. If you have a wider wheel, they make you buy it separately. So I have the original just sitting around for now. So far I have not been disappointed with any veritas products. I have two of their planes, some bench hardware, a tapering gauge (perfect for calibrating drill press/depth punch), marking gauge, and a few other things. My hat is off to our Canadian neighbors. As to the CBN wheel, Woodturners Wonders guarantees it for life. We'll see what that means in the real world with time. I can firmly recommend this setup, but agree with Don about the overkill. The same outfit sells a 1/4 hp motor, which would have been the way to go if I had understood what I do now. At some point I may rebuild it with that motor and convert my drill press to DC with this one. Very cool (pun intended) Jackson, I want to make one of these, but I"m a little challenged on the understanding of the wiring. I've been wanting something like this for awhile and have been compromising. Could you list any suppliers for these parts? I"m sure I'm not the only one that wants to know. I guess, mainly I'm after the speed controller and the motor. The others are pretty clear. jeff Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 13, 2020 Author Report Share Posted December 13, 2020 28 minutes ago, Jeff White said: Very cool (pun intended) Jackson, I want to make one of these, but I"m a little challenged on the understanding of the wiring. I've been wanting something like this for awhile and have been compromising. Could you list any suppliers for these parts? I"m sure I'm not the only one that wants to know. I guess, mainly I'm after the speed controller and the motor. The others are pretty clear. jeff Sure! Motor: https://www.amazon.com/VEVOR-Eletric-Electric-Permanent-Brushes/dp/B07DG3MQPC Drive unit: https://www.amazon.com/gp/aw/d/B00RW7LSXM?psc=1&ref=ppx_pop_mob_b_asin_title Wheel: https://woodturnerswonders.com/products/6-mega-square-1-2-arbor Motor shaft adaptor: https://www.mcmaster.com/43555A25/ Grinder rest: https://www.leevalley.com/en-us/shop/tools/sharpening/jigs-mounts-and-rests/32975-veritas-basic-grinding-set?item=05D1302 Grinder rest table for 1.5" wheels: https://www.leevalley.com/en-us/shop/tools/sharpening/jigs-mounts-and-rests/110472-table-for-1-1-2-inch-wheels-for-veritas-grinder-tool-rest?item=05M2303 The instructions with the drive unit will tell you what hp resistor, armature fuse, and ac line fuse you need. You can also call KB Electronics, tell them what motor you're planning to use, and they will tell you what you need. Note: there are much cheaper speed control units, but I went with what I thought was the highest quality unit I could. J Quote Link to comment Share on other sites More sharing options...
Jeff White Posted December 13, 2020 Report Share Posted December 13, 2020 Awesome Jackson, thanks. jeff Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 16, 2020 Author Report Share Posted December 16, 2020 I've now ground two knives, a chisel, and three plane irons, as well as a thick scraper. The chunky wheel absorbs heat so well I think the money spent on the variable speed controller was unnecessary. I have been able to grind every tool right up to the edge and never approached the level of heat my belt machine generates. If I were to do this over, I would just wire it on/off. Quote Link to comment Share on other sites More sharing options...
Don Noon Posted December 16, 2020 Report Share Posted December 16, 2020 10 hours ago, JacksonMaberry said: If I were to do this over, I would just wire it on/off. Sounds very similar to: get a low-speed grinder, and replace the wheels. Quote Link to comment Share on other sites More sharing options...
JacksonMaberry Posted December 16, 2020 Author Report Share Posted December 16, 2020 43 minutes ago, Don Noon said: Sounds very similar to: get a low-speed grinder, and replace the wheels. Pretty much. Low speed grinder, replace the wheels and stock tool rests. Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted December 18, 2020 Report Share Posted December 18, 2020 On 12/16/2020 at 11:07 AM, Don Noon said: Sounds very similar to: get a low-speed grinder, and replace the wheels. On 12/16/2020 at 11:50 AM, JacksonMaberry said: Pretty much. Low speed grinder, replace the wheels and stock tool rests. So what RPM is optimum for an 8” or 5” wheels? Quote Link to comment Share on other sites More sharing options...
Jeff White Posted December 18, 2020 Report Share Posted December 18, 2020 I am using a "low speed grinder" and it's 1750rpm. It's too fast for even one of those white "cool" wheels. Looks like maybe I could have just bought a CBM wheel for my "low speed" and changed the tool rest, but I'm thinking I would like it a bit slower than 1750. Don't know what's optimum. Quote Link to comment Share on other sites More sharing options...
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