Do not underestimate 1x30" belt grinders

If you have ground a few knives with a file or filing jig, than you already know how much work it is to first prepare the blank for grinding, grind the bevels and then grind the final edge once the knife is heat treated. In particular if you find out that you actually need to thin the blade after HT because you left it too thick before (ask me how I know - see Project #3 for details).

But you probably also already know that a good quality 2x72" belt grinder cost around $2000 (OK, you can get a simpler 2x72" like Grizzly for about $600 in US, but it Europe you are out of luck).

There are however ways in between and about the cheapest option there is is a 1x30" grinder. These seem all to look rather similar and may come with a small (125 mm diameter) integrated disc grinder and cost under $100/100€. The question is - are these any good? The short answer is ... YES

Still clean. The work rest for the disc grinder is not attached yet.

The grinder in question is marketed in Germany under the name Scheppach. The belt grinder has some limited possibility to center the belt (with a small knob on the rear wheel) and that is it. It is even possible to attach a vacuum cleaner hose on the bottom-left side (something that proved very useful alraedy). The exposed part is partially supported with a thin steel plate (barely visible in the photo above) and part is unsupported (slack belt). You can also remove the upped plastic cover and use the upper wheel for grinding curves.

Basic features

The 'platen' of the grinder is a relatively thin L-shaped (attached with 2 screws) piece of steel that flexes relatively a bit under pressure.  If you plan doing some more precise work you will probably want to replace it with something more stable, but  you will have to make it yourself. Still - the platen as it is is usable.

I would also like to mention the speed of the belt. On this machine it is around 13 m/s - that is pretty much spot on - in particular given the low power of the grinder. Important is, it is not super high speed grinder as with just 250W it would be way to easy to stall (which you can still do, but it can be avoided with a little experience)

The work rest on this particular grinder as made out of aluminium and is not particularly strong. It is attached on one side and it does not really allow to be set under an angle.

The 'platen' and the work rest.

The side cover of the belt grinder has an attachment point for a vacuum cleaner. Since I got the Metabo ASA 32 L industrial vacuum cleaner I use it all the time. barely any dust (steel or wood) gets away.

Side cover of the belt grinder.

The disc grinder has a bit more substantial work rest (though still made out of aluminium) that can be adjusted from 45 to 90 degrees. A plastic part can be attached that allows to attach a hose from a vacuum cleaner. This proved VERY efficient in minimising the amount of dust (in particular when grinding wood) that would spread across the workshop.

The translucent  cover of the top wheel can be removed and you can grind some curves around a handle.

From inside

Removing the belt cover you can see the bottom large wheel that transfers the power from the motor to the belt, the top wheel and finally the rear wheel which has an adjustment knob.

This adjustment knob has 2 functions (which would be adjustable separately on a more upscale grinder) It tensions the belt AND it allows for certain left/right adjustments.

Adjustment knob on the rear wheel.

How to set up

To attach and adjust a belt I found the following procedure to work the best:

1. Remove the plastic cover and unscrew the adjustment knob completely.
2. Put a belt on the bottom and back wheel - 1/2 of the width.  Hang the belt loosely on the screw next to the upper wheel.
3. Press with your left hand of the rear wheel and push it against the spring (towards the platen). 
4. Slide the belt on the upper wheel with your right hand.
5. Gently push on the belt from the side to get it fill width on all 3 wheels.
6. Screw the adjustment knob until you see the rear wheel moving (tensioning the belt)
7. Turn on the grinder briefly and see how the belt runs. If it is too far left or right adjust the rear wheel. If it keeps jumping off the wheels on the left irrespectively how much you adjust the rear wheel, than you will need to use a little brute force and push on the frame close to the upper wheel towards the right. I did have to do that. This will affect the belt alignment agains the platen, but it will run well without jumping off the wheels. 
8. Repeat the step 7 gently until you get the belt running stably with the adjustment know around the middle of its range.

Preparing to mount a belt.

Pushing on the rear wheel (once the adjustment knob has been screwed  loose).

Disc grinder side with the vacuum hose attached.
That big green thing in the background is the Metabo vacuum cleaner :)

Belts

The grinder comes with some sort of cheap aluminum oxide belt which will not last much when working with steel. To grind steel you will need to get belts that were designed for such purpose. In general this means to get Zirconia (also called ceramic) belts of some sorts. In Germany there are Klingspor belts available, I have got a few for testing, but I have not been too impressed (part of the reason was the grit - 24 is way too coarse and breaks off the belt easily).

Some really nice belts: from left ro right: 3M Trizat 'gator', Sait 7S #80, Norton Blaze #60 , Sait 7S #240

You basically need (want) 2 types of belts for the start (that is what I have at the moment)

• Ceramic belts (like Norton Blaze or Sait 7S) for bevel grinding or handle shaping. These belts are relatively hard and last a long time
• Softer belts (3M Trizact - 'gator' or 'normal' - these are available in higer grits and are great for removig scratches, or getting around the corners of a handle or a knife heel on a slack part of the belt.

I have also briefly tested Sait 7S and Norton Blaze belts. I have used Sait 7S in 40 grit to profile a blank (after rough cutting with angle grinder) and I have finished 6 blanks with single belt and the belt will do a couple more.

Norton Blaze in 60 grit seem to be the right fit for this grinder - they cat plenty fast (remember - this baby has only 1/3 hp) and seems to last well.

So - what can you do with this baby grinder?

• Profile blanks - this is so much faster than with a file AND i allows you to use a quick and dirty method of cutting your blanks with an angle grinder (the cheapest 'powered way' to do so).
• Grind bevels - there is quite some learning curve - the narrow belt does not make it easy to get even grind and the platen is not quite as sturdy, but it can be done - and it is of course faster than with a file.
• Final-grind bevels after heat treatment (care needs to be taken not to overheat the edge)
• Shape handles - you can use the slack belt part for easier rounding of the blades and the upper wheel for some radius grinding
• Shape bolsters
• Shape your hand-made fixtures and tools (i.e. to take off edges of a file if necessary)
• The little sanding wheel can be used (with some experience) to flatten/square blade steel and handle blocks. You would want larger disc sander for that, but hey, once it is there why not giving it a try.

Weak points

Not evetything is perfect though. With these simple machines you will have hard time to square things up, the 'platen' is rather weak and will flex under too much pressure making keeping constant angle harder. And, obviously, the narrow belt will make it harder to get even grind. But none of these little deficiencies is a show stopper. You have also very limited possibility to set the tension and position of the belt on the grinder.

A few examples

Grinding a bevel on a blade.

Grinding the glued WA handle to rectangular shape.

Flattening the sides of the handle with the disc grinder before final shaping.

Final shaping of the handle with the disc grinder.

Grinding to shape of integral handles (here birch bark handle).

General warning

When using the disc grinder (this one or bigger model) - be careful - if you do not hold the item you are working on firmly and the grinder bites into it (dents it in the process), it will send it flying across your workshop. Happened to me a few times with the WA handle shown above. So be careful and wear your safety gear.

Dust

If you start using the grinder (and in particular the disc grinder) to grind wood, you will find out that it will produce crazy amount of fine wood dust that will get everywhere. I finally broke down and got and industrial vacuum cleaner (Metabo ASA 32 L) which can be attached to simple plastic covers and can directly suck-away good 95% of the dust produced.

In General - steel dust is rather heavy and does not tend to spread quite as much as wooden dust. In particular the disc grinder will tend to fan the fine wooden dust over quite a distance, so using some sort of suction device really helps.

The costs

Let's be honest here - the cost of this little grinder itself will sooner than later be topped by the cost of the grinding belts. Remember - the worse/slower the belt cuts, the faster will the blade heat up as the hot material that is directly in contact with the belt is not being removed and all the work the grinder does is being turned to heat.

You should expect to pay around 2 $/€ per good quality ceramic grinding belt and  more for those awesome 3M Trizact "gator" belts. And you want them.

The vacuum cost me around 150€ (but it also helps to keep the workshop in shape). There are cheaper models for under 100 € that will do the same job.

Summary

The take-aways are:

• This is a little capable machine that will alow you to get decent results and to learn how to use a belt grinder.
• When grinding handle material you may need a vacuum that will keep the dust in check
• Be careful with the disc grinder - it likes to send stuff flying around.
• Get high quality ceramic belts for steel grinding (like Norton Blaze or Sait 7S). Cheap aluminium oxide will last just a fraction of a ceramic belt and is not cost effective.
• The cost of the grinder will be quickly topped by the cost of the belts

Please do not hesitate to ask questions or share your views or ideas :)