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Forum topic by DrTebi posted 04-04-2019 08:16 AM 1010 views 0 times favorited 24 replies Add to Favorites Watch
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DrTebi

294 posts in 3597 days


04-04-2019 08:16 AM

Topic tags/keywords: sharpening worksharp honing

A bit of a background story, skip this if you are impatient :)

Background Story
To build a new workbench, I bought some salvaged wood from a 100 year old barn in Brazil. It was supposed to be Peruba Rosa, and maybe some Cumaru, the seller wasn’t sure. I got 3×5 pieces for the legs, which turned out to be Peruba Rosa. Beautiful, and moderately easy to plane by hand and machine. For the top, I got 3×7 pieces, which are most likely Cumaru or some similar extremely dense wood.
The 3×7 pieces are just too big to maneuver over my jointer, and my jointer is a bit out of alignment on top of it (which is extremely difficult to fix, another story altogether). So I resorted to planing one face and one edge by hand; after that I can shove them through my planer.

So far so good… the only problem is, that this wood is extremely hard, and, to make matters worse, contains silica, which makes it seem like you are hand planing sandpaper. After about 5-10 minutes of hand planing, I need to resharpen my blade. I usually use water stones and a Richard Kell Honing Guide, but since my plane irons are a 2, 2-1/8 and 2-3/4 inch wide, it’s a bit difficult to say the least. It’s also quite slow, and if you have to do this every 30 minutes or so… tiring! So I looked for some other sharpening options…

DIY Worksharp Idea
As a sharpening alternative to stones and a honing jig, I came across the Worksharp WS3000 and liked the idea. But it isn’t exactly cheap, especially if you want to add some diamond lap discs in order to grind and hone on the machine. So I figured maybe I can build my own :)

Before spending any money, I looked at what I had at hand, and put this simple crude disk sharpener together:

This is an old belt-driven turntable. I increased the speed somewhat (maybe to around 100 RPM) by putting a rubber wheel over the motor shaft. I glued some sandpaper onto Melamine disks, and drilled a hole into each disk to fit the shaft of the turntable.

I also wanted to “wet-grind”, that’s why there is a bunch of plastic protecting the tonearm parts etc.

To get into the same level as the spinning disk, I simply made a platform (that partially hugs the platter) with a couple of 2×6 pieces underneath, trimmed to elevate the platform slightly above the disk.

Lastly I put together a simple jig to hold the plane irons, similar to what you may have seen for the “scary sharp” system.

OK, long story short: It works. It actually works really well, except for one thing: The turntable motor has way to little torque. I can only apply a small amount of pressure before it stalls. Eventually I disconnected the motor and spun the turntable by hand—this gave me a faster speed and more torque.

I was surprised how easy it was to bring the edge back (until I got the “wire edge”) with the 220 disk, and it also was quite quick to get a pretty sharp edge with the 1500 disk. Once the wire edge was removed, I was able to attack the Cumaru again for a while…

Please keep in mind this was only a crude experiment to check if this will work at all. Going from 220 to 1500 is certainly a bit of a big step… and there are probably dozens of other improvements I could make.

Here are some ideas I had:
  • Use a direct-drive turntable. These should have better torque, especially the DJ models. However, it is probably still far from strong enough.
  • Use a pottery wheel. It comes with most of everything that’s needed, a strong motor, nice platter to mount sanding disks, and is even meant to be used with water, so wet grinding wouldn’t interfere with electronics etc. Problem is, pottery wheels are not cheap. Even a “kick wheel”, which is basically driven by your foot kicking a large cement or cast iron wheel that’s connected to the platter, is not cheap.
  • Use a retired juicer (with a working motor…). This should be strong enough, but they spin too fast—one model I have seen spins at 3600 RPM.
  • Find another slower spinning motor and connect a turntable platter, pottery wheel, or other balanced disk to it.

What I am a bit confused about, is how to control a motor’s speed. I have seen PWM controllers, that appear to work well. But then there are DC motors and AC motors, and I am not sure if both can be controlled with that.
A Variac can also be used to some extend, but from what I read, it may damage the motor.

If anyone can offer some insight to the use of motors and controlling their speed, or if you have any other ideas or suggestions, please let me hear from you!

P.S.: Of course I could just buy a Worksharp WS3000… but you know how it is… we like to build things ourselves, it’s fun, and may even turn out better than the commercial option :)


24 replies so far

View Underdog's profile

Underdog

1280 posts in 2366 days


#1 posted 04-04-2019 11:15 AM

I saw a guy make a sharpening system out of an old food dispose-all unit. It’s a water proof unit, so you don’t need the plastic to protect your drive system. You also have enough power to drive the disk.

Just a thought.

-- Jim, Georgia, USA

View HokieKen's profile

HokieKen

8939 posts in 1469 days


#2 posted 04-04-2019 01:09 PM

There are lots of ways to do this but, doing it cheaply may be another story…

How is your motor now coupled to the turntable? Can you keep that turn table and use another motor to drive it? If so, see if you can find a free treadmill on CL, FB, etc. It’ll get you a DC motor with sufficient power and controls to PWM it ready to go.

Another option is a 3 phase motor with a VFD to drive it and use for speed control. At that point, you might as well buy the Worksharp. Which I have and highly recommend BTW. But I’m all for shop-made solutions when someone wants to tackle them :-)

-- Kenny, SW VA, Go Hokies!!!

View Tony1212's profile

Tony1212

309 posts in 2065 days


#3 posted 04-05-2019 12:46 PM

Bob Clagett at I Like To Make Stuff, just put a video yesterday about making a pottery wheel.

He used an electric scooter replacement motor, a DC motor. He added in a controller unit that has a speed control. I haven’t really looked into it too much, but it looks to come out < $100. And if it comes from an electric scooter, you’d figure it has to be able to move a 150lb person up a hill in San Francisco. That should be plenty of torque.

-- Tony, SW Chicago Suburbs

View DrTebi's profile

DrTebi

294 posts in 3597 days


#4 posted 04-05-2019 09:45 PM

Thanks for all your input.

The biggest challenge is to find a motor that spins at the right speed. WorkSharp uses a 1/5 HP motor spinning at 580 RPM, so I set out to look for something similar.

In most cases I would need a separate speed control unit, and I don’t know if I could trust the cheaper options (lots of reviews on burned out units…). Better ones would make things more expensive again.

But then I came across another option: A motor with a gear head. If the ratio is close to getting a speed within 300-600 RPM, I should be fine and would not need any other components to run the motor.

I eventually found a great deal on a 1/6 HP Leeson motor with a gear head that brings the speed down to 340 RPM. A bit lower than a WorkSharp, but since I want to use larger discs, that should be just right. The motor has a 5/8” arbor, onto which I could fit my ShopSmith sanding disk, or one of the 5/8” arbors, and figure out some way to mount discs with sandpaper.

The adventure begins… once I have the motor and something cobbled together, I will report back :)

View Francisco Luna's profile

Francisco Luna

968 posts in 3724 days


#5 posted 04-05-2019 10:03 PM

I remember these guys when I was an exchange Student in Mexico DF…....they use to go through the neighborhoods screaming offering sharpening service…...this could be the torque you are looking for, all you need is a differential to power the spinning wheel!

-- Nature is my manifestation of God. I go to nature every day for inspiration in the day's work. I follow in building the principles which nature has used in its domain" Frank Lloyd Wright

View MrUnix's profile (online now)

MrUnix

7309 posts in 2530 days


#6 posted 04-05-2019 10:16 PM

Get a treadmill (free off CL). Everything you need (and more) will be there except possibly a variable resistor to control the speed. DC motor, PWM speed controller, wiring, power supply, etc…

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View DrTebi's profile

DrTebi

294 posts in 3597 days


#7 posted 04-06-2019 05:19 AM



I remember these guys when I was an exchange Student in Mexico DF…....they use to go through the neighborhoods screaming offering sharpening service…...this could be the torque you are looking for, all you need is a differential to power the spinning wheel!

- Francisco Luna


Believe it or not, I have thought about doing that already :)
I just would have no clue how to make a differential, well, at least not how to make it good enough so that one can actually sharpen on the disc. The nice part would be, that you can sit down for once, and give your legs a bit of a workout after working (hand planing or whatever) with your arms all day.

View Francisco Luna's profile

Francisco Luna

968 posts in 3724 days


#8 posted 04-06-2019 07:43 AM

That would be great, in fact many of us are out of shape in need of good exercise….

This is my Miller Falls Crank drill, as you can see has a differential with two speeds…. by pushing the little knob on the center black casting, the crank can be removed and placed in the second hole with the second gear…...Im sure something like this a bit bigger can be found somewhere, an old motorcycle transmission….?...I am in the midst of other projects, but I am in need of some sort of sharpening system as well!


-- Nature is my manifestation of God. I go to nature every day for inspiration in the day's work. I follow in building the principles which nature has used in its domain" Frank Lloyd Wright

View DrTebi's profile

DrTebi

294 posts in 3597 days


#9 posted 04-06-2019 10:37 AM


That would be great, in fact many of us are out of shape in need of good exercise….

This is my Miller Falls Crank drill, as you can see has a differential with two speeds…. by pushing the little knob on the center black casting, the crank can be removed and placed in the second hole with the second gear…...Im sure something like this a bit bigger can be found somewhere, an old motorcycle transmission….?...I am in the midst of other projects, but I am in need of some sort of sharpening system as well!

- Francisco Luna


As much as I like the idea of an exercise-bicycle-horizontal-disc-sharpener, I think it would be too much effort to build one.

I like the WorkSharp concept, and it really isn’t too pricey. Nevertheless, if you are on a tight budget, and/or feel like experimenting a bit (like I do), you can cobble together something similar on your own, possibly even for free with some old kitchen appliance motor etc. You just need something that can spin a disc horizontally.

Here a guy used a food processor to make a home-made horizontal disc sharpener:
https://www.youtube.com/watch?v=rCEiM4c22iE

—-

Meanwhile, I have “upgraded” my turntable sharpener a bit: In my “recycled electronics” box I had a motor from a hand blender. I figured it might be possible to replace the turntable’s motor with that one… just as an experiment. The mixer had sort of a plastic arbor epoxied to the shaft, and, with the motor spinning in my vise, I “turned” a small groove into it for the belt to have something to ride in. Then I replaced the original motor with this one, made a little box for the electronics (just a bridge rectifier) and gave it a test run. You can see it in action here:
https://vimeo.com/328809257

I used this setup to sharpen a blade from an old Hercules hand plane that I found on the street. Without a jig, just by eye-balling a 25° and then 35° angle. It worked surprisingly well…

Of course it’s still far from perfect, it spins too fast, is noisy, there is vibration going on (hence the clamp)... but I like what I can do with this already :)

View Tony1212's profile

Tony1212

309 posts in 2065 days


#10 posted 04-08-2019 01:37 PM



Get a treadmill (free off CL). Everything you need (and more) will be there except possibly a variable resistor to control the speed. DC motor, PWM speed controller, wiring, power supply, etc…

Cheers,
Brad

- MrUnix

I keep seeing things like this posted here. I don’t know about other areas, but at least here in Chicago, the only free treadmills I find on CL, LetGo, etc. have burnt out motors – the very thing I’m looking for. Any treadmill with a working motor is at least $100 – $150. I’ve had my automated searches for over a year now.

-- Tony, SW Chicago Suburbs

View DrTebi's profile

DrTebi

294 posts in 3597 days


#11 posted 04-08-2019 08:11 PM


Get a treadmill (free off CL). Everything you need (and more) will be there except possibly a variable resistor to control the speed. DC motor, PWM speed controller, wiring, power supply, etc…

Cheers,
Brad

- MrUnix

I keep seeing things like this posted here. I don t know about other areas, but at least here in Chicago, the only free treadmills I find on CL, LetGo, etc. have burnt out motors – the very thing I m looking for. Any treadmill with a working motor is at least $100 – $150. I ve had my automated searches for over a year now.

- Tony1212


There are some on eBay, not sure if you can get away with less than $100 though. But there are other options. As I mentioned above, I have opted for a geared AC motor, which has the speed that I was looking for. I like this option because you don’t have to mess with VFD drives or other electronics, it should be “plug and play”. You may find one like that on eBay.
Some people use motors from food processors, mixers, garbage disposals… these are often noisy and may not have the torque needed, but if you can find one cheap or for free—worth the experiment. My hand mixer motor does not do too bad.

View BlueRidgeDog's profile

BlueRidgeDog

475 posts in 110 days


#12 posted 04-08-2019 08:36 PM

I am curious as to interest in such a sharpening approach. I have three stones with the last being an 16000 Shapton and the first two being diamond stones. I also have a buffing wheel with ruby rouge. I can hone an edge in about three minutes (the 16000 leaves a mirror finish) and can cut a new bevel in about five minutes. No power required and the stones stay in a tray by the bench.

Is it to be faster or to handle a wider variety of tools? I typically sharpen tools used during a project if they get less than ideal and all tools at the end. My end of project sharpening is typically 7 chisels, two card scrapers, five plane irons and two carving knives and the entire process is usually 45 minutes or less. What am I missing (not a rhetorical questions as I am starting to think that I am out of the loop on some way to do things better)?

View MrUnix's profile (online now)

MrUnix

7309 posts in 2530 days


#13 posted 04-08-2019 08:51 PM

I keep seeing things like this posted here. I don t know about other areas, but at least here in Chicago, the only free treadmills I find on CL, LetGo, etc. have burnt out motors – the very thing I m looking for. Any treadmill with a working motor is at least $100 – $150. I ve had my automated searches for over a year now.
- Tony1212

LOL – yeah, they don’t tend to hang around for very long. Your location is no different than mine – any random search will turn up plenty for $100 or more day in and day out. But if you are quick, you can find them for free, or at least really cheap (< ~$50); I did a quick search on the Chicago CL and there are a couple out there now. I’ve been able to snag 6 free ones in the last ~3 years or so. I just missed out on another one that popped up over the weekend. That one stayed listed for about an hour and then poof – gone.

Just a note though – I’ve never found one yet with a burnt out motor. Usually it’s something stupid, like a fried fuse, missing ‘key’ or broken control console (which you don’t need anyway). So I really don’t care if the PO says it’s working or not – just as long as it hasn’t been sitting out in the elements for years and has been reduced to a pile of rusted scrap metal. If they say ‘it just stopped working’ – jump on it!

Another note: Usually, the treadmill has everything you need, ready to go – even the power cord, on/off switch, inline fuse and overload protection. Hardest part is figuring out how to mount things. Newer ones may need a 10K pot for the speed control, but that is a $2 part at Radio Shack. Older ones, that have either a speed knob or sliding speed control, will be plug-n-play with nothing else needed.

In addition, you will get a boat-load of hardware, metal tubing, bushings, rollers, typically another ‘incline’ stepper motor, large melamine walking platform great for table saw extensions or router tables, walking belt which makes great non-slip pads and other related uses, etc…. they are small goldmines :)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View Craftsman on the lake's profile

Craftsman on the lake

2935 posts in 3768 days


#14 posted 04-08-2019 09:29 PM

This is a very simple and cool video on removing the motor and electronics from a treadmill to make a variable speed control for the treadmill motor. He mounts the control unit in a box with a potentiometer. Detailed and probably useful for lots of applications.
Ironically, I just happened to come across this today and I see MrUnix post above showing the same items.

https://www.youtube.com/watch?v=CeF1I18DhNc

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

View DrTebi's profile

DrTebi

294 posts in 3597 days


#15 posted 04-08-2019 09:42 PM



I am curious as to interest in such a sharpening approach. I have three stones with the last being an 16000 Shapton and the first two being diamond stones. I also have a buffing wheel with ruby rouge. I can hone an edge in about three minutes (the 16000 leaves a mirror finish) and can cut a new bevel in about five minutes. No power required and the stones stay in a tray by the bench.

Is it to be faster or to handle a wider variety of tools? I typically sharpen tools used during a project if they get less than ideal and all tools at the end. My end of project sharpening is typically 7 chisels, two card scrapers, five plane irons and two carving knives and the entire process is usually 45 minutes or less. What am I missing (not a rhetorical questions as I am starting to think that I am out of the loop on some way to do things better)?

- BlueRidgeDog


If your method works for you, then you are probably not missing out on anything.

One of the reasons why I started this experiment is, that my plane irons are too wide to mount into a sharpening jig (the ones with rollers on the side) to use it with my stones.

From my experience, it also takes a great many strokes on a stone to get the “wire edge”. I don’t have diamond stones, which would probably speed this up.

I have also found my hands suffering a bit from all that manual honing… this may sound a bit like whining, but since the wood I am trying to plane is so dense, I need to resharpen at least five times per afternoon… hence I thought let’s try a powered solution.

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