119 forum posts
This is just a quick 'show and tell' about this honing setup I just completed for my Myford ML10.
The inspiration for this project came from a recent video I found on Youtube. This video showed an arrangement for mounting a mandrel in a collet chuck to hold a diamond cup wheel so as to enable one to grind and/or hone lathe cutting tools. Naturally, a support table of some sort is also required. In this only do I really differ from the design I copied, opting for a different approach which will be shown in the photos below.
The first requirement was a mandrel to swing the cup wheels. I turned this out of a bit of leftover steel from the scrap bin. The shaft is 16mm which is the largest diameter that the ER25 collet system on my lathe can grip. The stub mandrel itself is 20mm in diameter to fit the holes in the diamond cup wheels I bought.
As the steel shaft wasn't really wide enough to support the diamond cup wheels to my satisfaction, I used some Loctite 638 to bond on a section of aluminum rod which was then turned to suit. The clamping plate is also turned from this same aluminum. Sections of steel might have been better, but the ML10 doesn't turn that fast (max 845 rpm) so that this connection won't really ever be under that much stress.
The finished mandrel worked a treat, so it was time to get on to the business of making a support table. The original design was just a long plate of steel bolted to a wide bit of rod, which is held in a massive chunk of steel which mounts to the cross slide. That design works but didn't offer quite the range of angles I wanted.
My own table design was (again) somewhat dictated by what I found in the scrap bin, ending up being a conglomeration of hot rolled steel plate and bar stock. I then used the freeware 3D program Blender to visualize what I wanted to create.
My chosen method of construction for this support table was to cut and mill the parts to form after which I joined it all up with the TIG welder, then milling the parts again as required to remove (some of) the inevitable distortion from the welding process. It pretty much worked out as planned.
Edited By JasonB on 16/09/2020 10:06:16
119 forum posts
Just below you can see the finished table.
It is not really so good looking as the computer model (what ever is?), but it functions quite well. The small holes in the top of the table are tapped for M5 screws in case I ever feel the need to clamp down parts or guides. The larger holes in the top of the table were an afterthought to allow an allen wrench to poke down through to tighten the cap head bolts in the T-nuts that secure the unit. As a construction note, I chose to drill spaced holes along the length of that bit of L-channel and then made plug welds in each one to join it to the plate(s)
I should note that I also used the Blender 3D program to 'animate' the action of the table so as to determine if the little slotted support was long enough (before I made it), but also to check that it had no interference in operation.
The front vertical plate of the table design extends down to (somewhat) protect the T-slots from grinding dust. Of course, anyone who decides to do honing on the metal lathe is well advised to cover everything and make liberal use of a vacuum cleaner and rags to clean up after any grinding operations.
I've already put this table into use and it works a treat. It isn't perfect, but it serves quite well and was worth my time and trouble. The only things I might change: (A) It would be nice to make some sort of screw adjustment for fine setting of the honing angle and (B) I think I might lightly mill the top of the table as that hot rolled plate is not completely flat.
Hope this inspires some of you.
|Martin Kyte||15/09/2020 22:16:46|
2064 forum posts
Well it's very well executed, but apart from my total aversion to grinding wheels anywhere near my lathe does it really spin the diamond wheel anywhere near fast enough? Fair enough you do show the bed covered but I would suggest that in addition to A and B you could add C replace the ML10 with a grinder motor fitted with the wheel of your choice and do your grinding someplace else.
Sorry to be a wet blanket and I really hope I have not offended you. The table is great it's just the idea of using the lathe to drive the wheel that gets me.
|Clive Hartland||15/09/2020 22:24:41|
2607 forum posts
ML10 highest rpm is approx 800rpm.
119 forum posts
@Martin, no offense take and I see your point. It would be really fine to have a dedicated tool grinder setup, but this little honing setup struck me as a fun project worth trying out in the short term. Aside from the cost of the wheels themselves the whole thing really only cost me nothing more than my time and those bits and pieces from the scrap bin.
As for results: Let me assure you that I'm getting a very nice finish on my lathe tools. But I'm no fool. I'm doing the basic heavy grinding and shaping of my tool steel on an 8" bench grinder. This lathe setup is really only meant for the final honing (a task that it does very nicely).
While one could want a spindle that spins a bit faster for these grinding wheels, it does work. The slower speed is actually a bit of a plus in terms of control. In fact, I would like to get my hands on some extra fine diamond lapping discs and (running the lathe even more slowly) end up with something akin to the 'Slowspeed Carbide Grinder' made by Stefan Gotteswinter (also on Youtube).
|John Olsen||16/09/2020 07:19:27|
|1089 forum posts|
I've got a purpose made diamond hone setup made by an American company and that actually turns its wheels quite slowly. The wheels are used wet, water with a little wetting agent. I don't think diamonds need to be used at any great speed, bearing in mind that diamond will oxidise in air if it gets hot. The final hone with an 1800 grit wheel gives a mirror finish on HSS or carbide.
18901 forum posts
They don't need to run fast? My Tormek runs at 90rpm and gives a surface speed of 62.5m/min, assuming that is a 100mm wheel then at 800rpm you will be getting 250m/min
|Martin Kyte||16/09/2020 08:09:57|
2064 forum posts
Ok, so it's fine regarding speed. Just need a water spray then. ;o)
As I said it's my aversion to grinding in the lathe when you dont have to, and I have employed a toolpost grinder before out of neccessity.
|duncan webster||16/09/2020 13:38:24|
2799 forum posts
You learn something new on this forum most days. Quietly confident that you had to go fast for grinding I went googling and found this
it uses 5" wheels and runs at 350 rpm, so it looks like my assumption was wrong. I think if you overheat diamond by running dry it turns to graphite, which isn't very abrasive. I used cubic boron nitride on my drill sharpening engine for this very reason.
Edited By duncan webster on 16/09/2020 13:39:50
|John Olsen||16/09/2020 15:47:42|
|1089 forum posts|
My own machine was purchased by my late father nearly forty years ago, and is an Accu-Finish. I see they are still going. I have no connection with them, apart from being very satisfied with the machine.
If it is hot enough, the diamond will oxidise to CO2, which is even less abrasive than graphite!
|Neil Wyatt||16/09/2020 15:55:56|
18240 forum posts
Probably unnecessary, but to be on the safe side a warning to beginners that although metal-to-metal clamping is fine for these alloy-bodied grinding wheels, grit wheels must always be clamped with card washers in place.
119 forum posts
Just thought to post this last image of the honing support table in a more finished condition.
I spent quite a bit of quality time ( probably way too much time ) cranking this support table back and forth on my little milling machine. The whole thing took simply hours to finish, mostly because I was doubtful of how secure the clamping of this part was. As a result I took only very tiny passes ( 0.5 mm ) to accomplish the task. Even then, the part was a bit wider than the travel of the Y axis on the milling table would handle and so the last 4mm of the edge farthest from the diamond wheel was skimmed off in the bench vise using hand files. The final finish was obtained with a series of flap disks, sandpaper, ending up with a Scotch-brite wheel.
The actual functionality of the support table has not been improved so very much relative to the time I put in, but the tools to be honed can certainly be moved around more easily. And, of course, there is that warm, fuzzy, good feeling of having a nice, smooth surface.
|Pete White||20/09/2020 18:45:26|
|114 forum posts|
Thankyou for posting your excellent work Ignatz.
I have just bought one off those cup wheels and mounted it on a 1/4 hp motor, using it free hand, works for me, need to up my game.
|Stewart Hart||20/09/2020 20:07:42|
651 forum posts
Edited By Stewart Hart on 20/09/2020 20:13:54
Edited By Stewart Hart on 20/09/2020 20:15:32
Edited By Stewart Hart on 21/09/2020 06:52:32
|Stewart Hart||21/09/2020 07:15:26|
651 forum posts
Sorry about not getting the video loaded I'd forgotten how to do it. all sorted now after third attempt
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