Grinding alignment jig

[Eric The Viking]

I finally collected my Axminster grinding jig yesterday morning from the post office, having had one of those phantom bellringer notes through the door on Friday ('You were out when we called.' Yeah? Four people who were in the house at the time disagree with you!). Royal Mail seem determined to put themselves out of business...

... but I digress. It looks nice; it will be rigid in use (with a bit of fettling with coarse sandpaper); it wasn't expensive. There were, however, no setup instructions supplied, but then it's not exactly a complex tool. I thought about it for a bit before deciding it might be worth making an alignment jig of my own, to get a tidy 25 degree or 30 degree bevel, prior to honing the final edge.

It's really a one-off setup, at least until the stone wears down a bit (and I don't have that many tools to grind!), so I want something obvious in use, as I'll pick it up only very occasionally, and it needs to be something with the minimum of precision required in construction, as I don't have the important tools set up and fettled yet.

So I came up with this, which I humbly offer up for criticism, etc.:

It fits over the spindle of the wheel (you need to take the cover off to do this, but it's only an occasional job). You slide the runner down till the angled edge just catches the circumference of the wheel (by eye), then pop a chisel or bit of flat plate into the Axminster jig, and adjust it until the plate (and the jig) is parallel to the angled edge, along the red line.

The result should approximate to either 25 or 30 degrees. It doesn't really take the blade thickness into account (you get the specified angle at the tool's edge, not in the middle of the ground surface), but it's most likely near enough for practicality, and should be quick to make.

Here's the parts:

Sorry about the Lurex colouring - slight oddity in output from Corel Draw.

It's supposed to be in 1/4"MDF or possibly even partly in hardboard(!), as it needs to be thin.

There are only two 'precision' elements:

- on the main bar, the lower edge needs to be cut on a radius from the spindle hole (and the slot needs to be parallel with it),
- on the sliders, the bevel angle needs to accurate WRT the two bolt holes.

I'm undecided about the slider design, but will probably do style 2 as (a) it's easy, and (b) it's one part less to lose.

I intend to use M6 domed, square ended coachbolts to hold the two parts together with wing-nuts (or spiked tee nuts as substitutes -- I'm a cheapskate!). Obviously, dismantling the grinder guard to fit it is a nuisance, but I can live with that.

What do the team think? Any good? Waste of time/rubbish? Is there a better, cheap alternative?

Thoughts appreciated...

 

[Chems]

Thats good, similar idea as the Tormek jig which you could buy easily enought?

 

[Eric The Viking]

That's good, similar idea as the Tormek jig which you could buy easily enough?

I hadn't seen the Tormek one (a glimpse of the prices for their actual grinders instantly put me off!). Fair dos to Axminster, it's only £13.00 from them - way lower than the cost of making my own and far quicker to use (no dismantling of the grinder required).

(later) I can see how the Tormek one works now.

I hadn't considered anything similar because of the accuracy required to make anything that complex. Their cam. which substitutes for getting the wheel tangent, is a precision element and isn't necessary in my design, BUT mine would be a much greater fiddle to use.

I think mine would be much more accurate though (but that doesn't matter really), and I strongly dislike magnetized tools when not necessary, especially anywhere near steel filings, though I guess you could use a flat bearer on the tool's back, instead of a magnet.

Theirs is hard to copy (otherwise I'd make one to see how well it works).

Many thanks for that - it's food for thought. If I can use the circumference curvature somehow to get the radius, there would be no need to dismantle the guard (although they, too, need the radius to be known - difficult on a guarded stone.

I suppose I could just use Sellotape, and stick it around the circumference, pull it off and measure the length, then divide by 2pi to get the radius! (wanders off, muttering the while... )

 

[Chems]

The guards come off fairly easily on my grinder so thats not to much off a worry. If you need any measurements to help you out I'd be glad to measure mine as best I can. I only ever set my roughly on the wheel size and the results have always been good.

 

[woodsworth]

I very much like the jig you made. It is something we can make on our own and just looking at your drawings helped me understand the angles much better. I'm so used to just popping the blade onto the rest and adjusting it to create the same bevel that i just haven't given much thought to it.

Thanks for sharing this.

 

[George_N]

I have the Veritas grinder jig and after faffing around with the angle setting thing that came with it I got myself the Tormek anglemaster. Very quick and easy to use and easy to reproduce bevel angles. It is made to work with the larger Tormek grinding wheels (8" or 10") so a 6" high speed bench grinder is at the bottom end of its working range. I guess that the angles will go off a bit as the wheel wears down but I don't use my grinder enough for that to be a big problem.

 

[tekno.mage]

The Tormek widget is really quick and easy to use - and it's sturdily made, so should last well.

tekno.mage

 

[squib]

I like that alot and it will be very accurate regardless of wheel wear.I might have a go with some perspex if you dont mind......must get a grinder guard

 

[Eric The Viking]

I like that alot and it will be very accurate regardless of wheel wear.I might have a go with some perspex if you dont mind......must get a grinder guard

I ought to do a quick update then, before you get too stuck-in:

I made up a prototype, but:

-- I couldn't use the grinder spindle in the end as my el-cheapo one doesn't have enough thread projecting, and I didn't want to use it unguarded. Instead, I found the centre of the wheel guard, and drilled it for a 20mm M4 bolt (with nut and anti-shake washer), facing outwards, which is now a permanent fixture on the grinder. The head is small enough not to foul the end of the grinder's shaft inside the guard.

-- the actual gauge has been made out of Meccano pro-tem, partly so I could experiment and partly because it needs a Z-bend to align in front of the wheel, to cope with small chisels.

It did actually work really well though, for setting 25 degree angles. I know this as I easily got the re-grind to start right in the middle of the existing bevel.

The final version might end up in metal or Perspex, prob the latter as it's easier for me to finish nicely and I have a few offcuts around.

Hope this helps. I'll post a few pics when I have a moment, but the machine's not set up right now and the bench is in use for other tasks.

Cheers,