I am cobbling together my grinder. It's too cool in the shop to do much work on it, but spring is on the way. I've started with a 2 hp 3 phase WEG motor (Kijiji $35), some wheels from a guy on eBay and some 2" and 1.5" H.S.S. and scrap steel from the bin and metal supermarket. As a result of my work connections I scored a 3 hp VFD that has a single phase 240 V front end. I estimate I am into this for about $450 which includes the VFD. I reckoned that a nylon caster (Casterland) for a drive wheel would have been a bit dodgy, but we spun it to 4000 rpm on a VFD and she's smooth as. If I reduced the diameter from 4" to exactly 3.82", one revolution would be 1 foot. (3.82" * pi = 12") Then a tachometer would tell me the surface feet per minute. Sound about right? Thanks to Alaskabearhawk for his elegant design ideas. She's in need of some electrical work, paint and finishing touches, but I'll post more to let you know how it's coming along. Anyone who wants to build their own only is feel free to ask. AutoCAD drawing: Test fitting the belt and motor positioning: Dan
looks great little more black paint , then we can call it the killer bee ,i named mine the ultimate headache , no wait thats my wifes nick name lol , any how where did you get that drive wheel dan? i wish i would have went with out the pillow blocks on my set up . as i was worried about the speed of the 3640 rpms on a direct drive .
Hi, this is totally not approved for the application. LOL The drive wheel I am using is actually a nylon caster I bought from Casterland. I spoke to the guys there and one rep suggested this. I popped the bearing out and pressed a bushing in with a hydraulic press. This reducer was required as my motor has a 7/8" diameter keyed shaft. I spun it on a VFD in a bench test at 5200 RPM and it's smooth as silk. I might be concerned about using a cast iron wheel at higher speeds in case it decided to grenade on me. I am planning on installing a tiny neodymium magnet in the rear face of the wheel to trigger my tachometer (via Hall effect IC). This will count RPMs, but the circumference of the wheel is 4" and 4 x pi = 12.56". The surface feet per minute will approximate the RPM. Ideally I would reduce the diameter of the wheel to 3.82" and get better SFM accuracy, but lose some speed. Luckily the VFD will make up for this. All fun and games. I've had to add a spacer here, a washer there, some shims here and there. What kind of issues did you encounter with your setup? Dan
i had longboard wheel for my alignment wheel with tape on it .and still have longboard wheels as my two contact wheels on my platen . and the first drive wheel i got made was not snugg to the shaft . got new drive wheel made , but its not crowned so i have tape on it so the belt dont fly off.running much better now .i dont have much faith in the pully system as being totaly straight . wish i would have went to direct drive from motor . i still have an issue when the belt is travelling over my platen , it feels like there is something on my belt which makes it feel like something is bumping or hitting all the belts that i have used while im grinding .put on another harden steel platen and grinded it flat and still the same problem . then tried to put a graphite pad over the platen , and still the same problem .still works though , just annoying . i do plan to buy a new drive wheel and two more contact wheels from a supplier soon .but its all about the money as of right now .
The bump in the belt is likely the tape at the seam. I've been using on-board wheels for a while now and I would use them again. I find they make an excellent contact wheel. Your belt wondering is likely because all of your wheels are not perfectly straight.
The pillow blocks and shaft are extra bits to align. I gave myself some slotted holes when it came to mounting the motor. I had to adjust the motor shaft so it was perpendicular to the belt path. As well I had to put two shims under back of the motor to square up the shaft in the other plane. It would seem that the heat from welding the upright pieces causes and tiny bit of warp in the base and something went out of square. Either that or my bandsaw was set to cut at 88°!LOL Like Icho said, the bumping is likely the belt joint when it hits the top of your platen. Try a chamfer or round the top edge a bit to make a more gentle transition. A sharp 90°edge will want to catch more and make more of a thump each time the joint goes past. I would think that eventually this will wear and chamfer itself. The best part is that your machine is working and you are making knives! I haven't been making knives as much as I have been making grinder. Got to get back to the real craft. Cheers! Dan
icho thanks for your relply . good idea dan . i will go and round of the top and bottom edges of my platen tonight .. ive tried to get those wheels and pillow blocks all aligned many times over though . i just dont want to take the tape of the drive wheel again as it is now working not to bad lol. hey dan why do you have two tubes on your frame instead of just one ?
The other tube is for future use. I was planning on a slide-in tool rest in there. I guess it could be used for a 2" height adjustment for an attachment, or second attachment, tool rest, jig or what-have-you can go . I've seen similar designs (Wilmac) that have two or more receivers. When I make the single contact wheel attachment it may go in the top or the bottom receiver. I am thinking about where to put the task light, and now I have an idea! Stay tuned... and thanks!
ok got ya . nice web site you got . i went to download your templates and i did something wrong and i had pages coming out like crazy . lol
I am excited this morning to have the VFD hooked up and running if only for a tracking test. Ran the grinder at 20 to 60 Hz. Tracking and adjustment is going well with a Y weight belt. For test I grabbed two different extension cords and got a hot from each. A bit higher than I was expecting. So now I am waiting for the tachometer to arrive and we'll be finishing the electrical up. I know it's early, but ... Dan
Good to hear that it seems to be running smoothly. Looks like you're almost ready to make some knives with it.
For those who wanted a progress report, I've uploaded a short video of my grinder build (still a WIP) so far. With the mechanical/alignment concerns out of the way, I will focus finishing on the electrical, add a task light and make a stand to hold the VFD enclosure. The operator control panel will feature a tachometer showing Surface Feet per Minute, Start/Stop/Forward/Reverse, DC power etc. Ya ya, excuse my messy shop. When I get going on a project it's like a tornado hit the place! I can't wait to get this thing permanently setup in my shop and start grinding. Files are great, but I'd rather be uploaded them! Stay tuned for all the gory details in my blog. Dan
Update: Grinding now! A few more details to shore up like a stand to hold the attachments, but we're really close now. VFD Enclosure wiring: Getting up to speed: This is where it gets fun. The blaze chews through 154CM like butter at 4000 fpm. Goodbye hacksaw! D
