I started this blog post ages ago, and add bits to it occasionally. Now I’m almost happy with the way it runs, I figure I should post it up and let you all see it in all it’s hideous glory.
This story begins with a $69 bench grinder with attached belt grinder. THIS one to be specific.
This is the grinder from Bunnings.
There is nothing similar for close to this money. However, of course, you get what you pay for.
To start with, its very underpowered. That was kind of expected, but I thought it might do. The biggest problem though was getting it to track correctly.
The tracking mechanism was horrendous, and it would take 10 to 15 minutes to get the thing to track right if you changed belts etc… and the pressed sheet metal parts would bend all the time.
I tried to use it as is, but fairly quickly started modifying it to make it suit my needs better.
Modifications Phase One – Simple tweaks
Here is the grinder before I begin any modifications on it
I began by modifying the grinder to work suitably with my needs, rotating the belt so it ran vertically, and adding a new work support that was nice and large.
A small template I made to make re-drilling the holes in the case of the unit easier
The holes drilled in the grinder case. The slots you can see are the original mounting positions
Here is the grinder after the modification. Much easier to use.
This worked OK, but the issue of belt tracking still existed, so on went the modifications.
Modification Phase 2 – Fixing the tracking, and going bigger
Here is an overall shot of the grinder, now running the longer belts.
Here is a close up of the tracking system I make. Far from perfect, but it kinda worked.
Now, I was getting sick of how hard it is to get the grinder to track right. the mechanism was so bad, it was almost impossible to get it to run right. So I set out to make a new tracking system, and while I was at it, extend the length, so I could fit the longer 48 inch belts.
The tracking system is made from angle iron, and uses some parts left over from the previous tracking system, mainly the tension spring.
Now, this tracking system is not perfect, but Its a heck of a lot better than the original system.
Modification Phase 3 – chuck everything out and start again.
OK, at this point, its hard to call it a modification, its basically a new grinder. All that remains of the original grinder are the drive and tracking wheels. They seem to be holding up so far.
I had a 400 watt electric motor from a pool filter pump I had kicking about, which I originally picked up to make a disk grinder out of. I noticed that its shaft is exactly the right diameter for the drive wheel of the Ozito grinder.
Using some scrap metal which I salvaged from a wall support from a CRT TV as the basis for this grinder, I’ve constructed a more traditional style belt grinder.
This grinder now works much better than any iterations before it. It does still have its ideosyncracies though.
The gas strut I’m using is too strong, and puts way too much tension on the belt. Unfortunately, due to construction, I can’t move the location further down the pivot point, to reduce its leverage effects, as the main support gets in the way.
Modification Phase 4 – Further Improvements.
So at this point, I decided to change directions with the way I was doing the belt tensioning. I moved to a telescoping pillar style method, using vertical shaft of the grinder as the outer motion point. It uses the same gas strut for tension, but this way it provides less force on the belt, and things run pretty nicely.
The grinder as it stood before receiving the wheel and platten update.
After that, I felt what was holding me back was the wheels on the grinder. The skateboard wheels I have been using have a slight taper in one direction, that makes keeping the belt straight a little difficult. I could try and correct the taper, but in the end, I chose to simply replace them with proper grinder wheels.
The wheels I’m using came from Ebay, all the way from Poland from THIS store (no affiliation, just bought them from here). Being custom made for the purpose, they are a lot more solid, and are actually square compared to the slight taper the skateboard wheels had.
This is the wheel set that I bought for the grinder. Currently I’m not using the drive wheel.
My current frame for the skateboard wheel assembly wasn’t going to work for the new wheels, so I went back to the drawing board, and started fresh. Some more scrap steel from the brackets and bits & pieces I had lying about, and I had a one piece frame, and I didn’t have to worry about welding bits of steel together in the same plane like I did with the original.
Laying out the new platten / wheel assembly
Getting things lined up on the new platten assembly
Here I align the work platform and receiver before welding it on.
Here is the grinder with its new wheels. I’m yet to mount the actual platten in this image, but you can see how it looks at least.
It’s been quite a journey from a crappy, overly cheap bench grinder with attached belt sander, all the way through to a slighly more powerful grinder that functions a whole lot better. There are things I’d change. If I were starting again, Ideally, I’d avoid the bench grinder all together, and just start with a set of the wheels I posted, a motor that suits the wheels and a nice pile of fresh steel. Its always good to use what you have lying around, but often you get nicer results by investing some money and doing things properly.
Now I’m fairly happy with it’s layout and operation, I’m happy to let the grinder’s evolution to rest here for a little bit. It’s working as well as could be expected, but there is always something else to tweak. What I want to do now is USE my grinder to get making some things, specifically a few knives.
And for you all that read though to the end, here is a video of me talking about the grinder, and it running: