Hi Jon,
thanks for taking the time to share all your thoughts!
Matt, I assume this is still a future project for you, as you are just wrapping up (or did wrap up?? I've lost track) your WT drive project?
I don't know how much space you have, but separate machines might be best. Diamond coated wheels would be best for honing carbide bits. It seems to me that the 1/3 HP motor would be great for that. Are those coated only at the edge? If you have fully coated discs (seems unlikely?) then you don't need to have a variable speed disc grinder. You can vary the sfpm by the distance from the center of the disc. In that case a simple direct drive build makes the most sense to me.
I would skip building the 1" belt sander if I were you. If you want that size just grab the HF unit and modify it as you see fit. Personally I'm making a 2"x72" because that is the best bang-for-the-buck with belts because they're used by roughly 95% of knife makers. Talk to the fine folks at preferredabrasives.com if you have any doubt. They stock 2x48 in a good range of belt stock, but they have EVERY option in 2x72. There are other distributors with wider selections, but these guys are a small outfit trying REALLY hard to play in the big leagues and I'm very impressed with them. They're developing a strong social media presence as their primary marketing, so it's easy to find people talking about them who have used them extensively. I emailed them some specific questions about belt selection for shaping and sharpening HSS lathe bits and I got a detailed, non-scripted response in like 20 minutes.
The key differences between using 2x48 and 2x72 are the economics (like custom cables, the length makes far less difference to the price than the actual assembly, so the extra length costs very little more), and you have more abrasive in use providing longer life from each belt. Additionally by having a longer belt there is more time for it to cool between passes, keeping your workpiece cooler and again increasing the life of the belt.
yep, finished the DP conversion and it's working like a dream, love it to bits! This is still on the list, especially since I found another treadmill, this one with a 2.5hp motor
Slowly waiting for the wife to not use it for long enough so I can break it down and scavenge the bits I want. I'm planning on building a powerhacksaw first as I need some kind of motorised saw more than I need this right now, so the 1/3hp motor will be perfect for that. Whether or not I get to the grinder before the end of the summer and the start of the semester I don't know, perhaps, perhaps not, but it's still on the list.
Currently leaning towards a 2x48 grinder - i don't have the space or the materials for a full on 2x72 grinder (plus this'll have to be moved next year, so weight is an issue) - and still with a disk grinder. I'm planning on having the disk and belt drive wheel on the same shaft, with a pulley in the center, driven via belt by the motor. Ideally a couple of different poly V pulley sizes so that with the variable speed on the motor I should be able to cover a range of speeds.
The diamond coated disks are coated on the face, as far as I can tell, not the edges. I'm still thinking through an easy way to change disks out, so I can have a couple of different grit papers as well as the diamond disks and swap between them without too much hassle.
I imagine you've looked into this extensively, but as I've been planning my build (in the back of my mind for about 2 years, and as actively as my family life allows for the last 2 weeks) I have found YouTube to be the most helpful resource. Terms to search for inspiration:
KMG and KMG Clones
Knife grinder
DIY belt grinder
2x72 grinder build
Wilmont Grinders
Oregon Knife Maker
Alaska Bearhawk grinder
Treadmill grinder
Grinder contact wheel
Grinder small wheel attachment
Belt grinder platen
And so many more you'll find through related videos there. My own design ended up being a combination of features from others I've seen and a small twist of my own: multiple accessory arm size options (2"x2" like everyone else, plus 2"X1" and 1"X1") so I can use whatever makes the most sense for my current application and scrap on hand.
yeah, I've been looking at lots of different builds, plans and videos (same with the powerhacksaw!), picking up different ideas. Many of them are fabbed with skills or tools I don't have yet, so I think this would do fine for a 1st iteration and then I could always get fancier as my skills/ tools improve. Especially once we settle somewhere and I don't have to worry about moving my tools again.
Oh, also, my plan is to use a contact wheel for hollow grinding lathe bits, then final sharpening on a flat platen (I have a piece of stainless just begging to become an abrasion-resistant (relative to the A36 I'm using for the rest of the build) platen) then a stone or fine sandpaper on glass for honing. That way the final sharpening and touchups only have to work on the very tip, much like a microbevel in woodworking plane irons and chisels. I have an 8" rubber contact wheel, but I plan to make a 10" (the largest I can do on my lathe). I intend to learn how to cast a urethane tire around an aluminum wheel, and I would like to serrate/sipe the tire for better cooling as well.
Finally I'm planning on incorporating a compact cyclone dust collector (all HVAC leftovers for handling hot grinding dust) powered by a spare mini shop vac.
I still like the idea of having a contact wheel, but I just can't see how I can easily incorporate it into an upright design right now. It may be one of those things that I realise I need after using it for a while, in which case I can redesign the grinder to incorporate it.
