Thread: Using a surface grinder but not for surfaces

Hi Michael, don't know if you are into woodwork, but a friend of mine has a son that sharpens jointer and thickness-er blades on his SG.
Kryn

Michael, before dropping too far down this rabbit hole just be sure you will have sufficient Z under the wheel to be able to mount the grinding fixture, collets, and cutter itself. I have one but didn't have the Z to get it to work. I may not have had the 5C collets at that stage and will check again when I get home if you like?

I have both a Darex E90 end mill sharpener and a T&C grinder, both are designed to grind both the ends and sides of the cutters, the Darex in particular is very easy to operate and the air spindle works well. I've heard the adapters for the surface grinders work quite well, but will only grind the ends of the mills. There have been a number of projects in MEW over the years on adapters to grind end mills on conventional bench grinders, and that could be a solution too.

On the other hand a T&C grinder sure is a versatile bit of kit, and I'm pleased to have acquired one. They're not too space hungry either, so maybe something to consider.

I use mine for lathe tools and endmills. It's nice to make a radius toolbit with one. Similarly its nice to make a lathe tool where You can see the clearance is perfect and the size is spot on, not to mention sharper than done by hand. Pic of fixture later.

Originally Posted by Pete F

On the other hand a T&C grinder sure is a versatile bit of kit, and I'm pleased to have acquired one. They're not too space hungry either, so maybe something to consider.

Funny you should say that as I had a T&CG but all it did was take up space. I moved it on a while back and the SG is sitting roughly where it was. The problem with that particular T&CG was that it was free standing so needed space around it as well as it's foot print. I also thought that the Z feed on that T&CG was too coarse to do fine surface work (which was my main motivator for getting a proper SG). The SG is bench mounted, so I don't lose as much space.
I have roughly 6" of Z. I haven't got any 5C collets (and don't really want to get any either), but the grinding fixture I pictured is a recent variation that uses ER32 collets, so takes up less Z anyway. I currently have ER40 and ER25 collets though so it becomes a choice of buy one of the unit pictured or make one that takes ER40 collets.
Most of extensive collection of blunt end mills I have only have a chipped corner or two so probably one of these fixtures would do 90% of them (may have to shorten the others a little to clean up). As for lathe tools, I would like to be able to grind accurate angles for threads and other (straight profiles), Thanks to Pete I have a couple cup wheels so could mount a small table off the front but would like to see if anyone has a fixture that does not rely on the operator accurately setting both angles (that is, a fixture where you set the angle on one side and then by some strange and arcane means the tool is flipped/ rotated/ twisted so that the other side is symmetric to the first face.

Michael

While I used to similarly grind my lathe tools on the surface grinder, I now use the T&C grinder for that, however the surface grinder does a great job of lathe tools. Just set them up in cheap multi-vice using a digital protractor to set angles. Rigidity is of no real concern as it's just light grinding.

I'm more than happy to run some cutters through the Darex if you want to post them over. Just be sure to allow a couple if weeks for turn around however as I'm super busy with work at present and it's only getting worse.

I'll look in to that fixture when I get home, we may even be able to work something out with my old one if it helps, as I can't see myself needing it. Keep in touch regarding that if you like.

All ideas welcome, so please post what you've got or seen (or even thought).
A bit over half a page down http://www.chaski.org/homemachinist/...p?f=42&t=56591 is an interesting jig -


(that post is the only one with photos)
I like it because while you have to cut the angle accurately in the jig, using it for grinding individual tools then becomes easy. I have a multi angle vice that occasionally gets used for compound angles, but would really prefer something that has hard stops so the angles are repeatable and independent of too little sleep or too much coffee.

Kryn, I don't do much with wood but my thicknesser is 12", the SG travel is only 10" - hmm.

Michael

The issue with that I think Michael is that the angles are preset and looks to be mainly (or only) in one plane.

I have one of these universal vices set up on my T&C grinder if you want to set angles. http://www.ebay.com/itm/SHARS-UNIVER...-/300876103862

Having said that, in reality don't overlook the humble ball mount vice, at least as a temporary solution. Using a digital protractor it's quite accurate and repeatable, at least to the accuracy required to grind lathe tools etc. The protractors are accurate to fractions of a degree and that will do me. The vices are a little fiddly to set up in that you can't lock one plane while adjusting the other. On the other hand the universal vice can be a little large and cumbersome at times.

The camera angle hides it but from the write up I think the vertical is tilted over 5 or 10 degrees to give the side relief (the other way would be to tilt the channel the tool sits in to give the relief). The fixed angle thing doesn't worry me too much as for non critical tools I'd probably still grind free hand. Making up a 60 degree fixture and/or a 55 degree fixture would cover 90% of my needs so worth considering even as a stop gap if nothing else comes along.

Michael

Sure, I got that too, but the point was more that the angles are fixed, and while I'd think it would be possible to make a device with, say, interchangeable triangles for example to set angles, the back relief would be fixed.

Just thinking on the fly here, and rather quickly as I'm getting ready for work, but maybe what would become the side rake isn't that important if it's fixed, as it's rarely changed anyway regardless of material.

As it was pictured I thought the jig would have limited use, as I find once a thread tool (as I guess he's grinding) is made, it generally only needs touching up between uses. It seems this jig is good for just one angle. However perhaps if it was modified as I suggested, where there's a central triangle with a centre pivot, and the tool is clamped to that? Instead of changing triangles, just pivot that central triangle to set the desired angle. For tools that use back rake you'd need to grind that separately, but that's no big deal, and not required on thread tools anyway.

Hopefully that makes sense.

Tried an experiment today -
I've had this thought kicking around for a while and as I was at a loose end today thought I'd give it a go.
I cut a small piece of strip (75x10mm) and then after truing up an edge, took the head 5 degrees out of tram. I then swiveled the mill table around 30 degrees and using the in/out feed, cut a rebate in the strip (other end to the trued edge). I then pivoted around to 30 degrees the other way and repeated. (you could swivel the mill vice I guess but I can't remember where I put that bit)
P1020646 (Medium).JPG P1020647 (Medium).JPG

This was then taken to the surface grinder and held against a mag block. Using a small clamp, a piece of tool steel was held first one side of the rebate and then the other and ground. Posed picture but you get the idea.
P1020649 (Medium).JPG

This is the result -
P1020650 (Medium).JPG

A 60 degree threading tool with 5 degrees side relief (ignore the top - this was a random grab of old tool steel). Future enhancements include finding a more suitable looking clamp and maybe a spiffier base to hold the jig plate. The nice thing is that this jig will take a variety of steel sizes and takes up very little space, so I can make up jigs for WW, ACME, poly vee belts and so on and they can just live in the bottom of the drawer (could even use both ends of the same piece of strip too). Because the angle setting is done by the jig, it also means that tools can be sharpened in batches ready for use.

Michael

That's neat. Maybe you could make the angle part replaceable and pin different jigs to the back part, that would save making a lot of different jigs. It's likely the 5 degree side rake will be similar irrespective of tool, and the just swap out the 60/55/30/etc degree plates as you need them?

Yes, I've been thinking about doing it that way. In reality there are only probably only 4 or 5 specific grind angles that are critical, so 5 plates (or 3 if double ending) and you are set.

Michael

Yeah I guess so. I've got 60, 55, acme/trap, and Schaublin buttress tools, but can expect to probably need to grind conventional buttress and or reverse handed of one or both of those as they're not symmetrical. I've not yet needed to cut and v belt pulleys and have used store bought ones, but think I will need to sooner or later. Plus regular turning and facing tools, and I think you could set up your jig to do them too, so that's starting to add up. Anyway, just a suggestion, as it wouldn't be difficult to pin a plate in.

Where did you get that magnetic block btw? I need some for mine, they would be handy.

The blocks are from a set I bought on US ebay (2 square, 2 V). Made by Geo. Scherr and called Magne Blox. (can't see any there at the moment)

Michael