9 Attachment(s)
Thin Kerf cutting wheel attachment for bench grinder
If you don’t want to read the intro just skip ahead to the pics.
From 2007 until I got my 6 x 4 metal cutting bandsaw in 2011 the main way I cut metal was with a either an angle grinder or a thin kerf cutting wheel in an a small (8” blade) woodworking table saw. When I got the bandsaw I thought, well that will be the end of the little table saw, but I still used it quite a bit especially for cutting plate so I then bought a plasma cutter. At that point I really needed to reclaim some very scarce shed real estate so I restored the woodworking table saw and gave it to my son.
Although I’m happy with what the bandsaw and plasma cutter do, within a couple of weeks I really wish I hadn’t given away the table saw that but it was too late to get it back. The things I found it useful for was cutting small things like bolts, or bits of tool steel, and cutting into the ends of bars and rods. My hands aren’t steady to begin with but an angle grinder just makes it worse. Plus I really don’t like the noise angle grinders make.
I had in mind purchasing a small/cheap table top table saw and putting a thin kerf cutting wheel in that but recently I looked at moving my multitool finisher onto a variable speed GMF grinder I converted and this got me thinking and this is what I have come up with.
Standard GMF guard mounting setup normally used to hold the wheel guards.
https://www.woodworkforums.com/attach...d=352660&stc=1
Variant on multitool finisher attachment baseplate made out of 5mm plate
https://www.woodworkforums.com/attach...d=352659&stc=1
Additional 50 x 6 mm arm - you will see why this rm cannot be combined with the baseplate a bit later on.
https://www.woodworkforums.com/attach...d=352658&stc=1
100 mm plastic V-ribbed pulley from an old running machine I picked up at the side of the road..
There is a homemade 50 mm diameter steel hub with a 6mm keyway between the hub and the plastic pulley.
https://www.woodworkforums.com/attach...d=352657&stc=1
Bearing assembly and shaft. Inside the assemble are two 32 x 10 x 12 sealed bearings.
The allen screws are from an old washing machine I stripped down for parts last year
https://www.woodworkforums.com/attach...d=352656&stc=1
Shed made25 mm V-Ribbed Al pulley with 4 mm keyway and end-cap screwed into shaft
https://www.woodworkforums.com/attach...d=352661&stc=1
6 rib V-ribbed belt - also from running machine. Now you can see why the arm as to be separate from the main base plate - as this allows for adjusting belt tension.
https://www.woodworkforums.com/attach...d=352662&stc=1
On top of all that rides a small table made out of piece of 2 mm thick SS.
Here it is before the slot for the thin kerf wheel is cut
https://www.woodworkforums.com/attach...d=352663&stc=1
The table is hinged at the rear so it can flip up out of the way to get access to the wheel changing hub/nut.
The U- shaped gizmo at the end with the sprung screw pulls the table firmly down against the main arm
https://www.woodworkforums.com/attach...d=352664&stc=1
More to come.
3 Attachment(s)
Thin Kerf cutting wheel attachment for bench grinder (part 2)
To cut the slot for the blade in the table top I just attached a fresh wheel and slowly dropped the table onto the wheel so it cut its own slot.
This effectively gives it a zero width throat which is better than the old table saw which had ~5 mm gap either side of the wheel and I was forever losing bits and pieces down the gap.
The other advantage over the table saw is the depth of cut has been increased significantly (by some 15 mm) and it is ~5 mm more than for most angle grinders
The disadvantage over an angle grinder is that the wheel cannot cut at a tangent to the work so the cutting is not as optimised. Nevertheless it does a pretty good job.
Here it is cutting its own slot.
You can can see there are countersunk SS screws that hold the top onto the hinged top frame.
These SS screws are one of three things I spent specific $ for on this project - the other two were some 25 mm steel rod from the steel merchant and I did buy a new cutting wheel.
https://www.woodworkforums.com/attach...d=352667&stc=1
Here are another couple of views of the table top folded up out of the way for access to wheel change.
https://www.woodworkforums.com/attach...d=352666&stc=1
https://www.woodworkforums.com/attach...d=352665&stc=1
Now I'm going to play with it for a while before I disassemble it and pretty it up.
Here are a few specs
With a 4:1 pulley it's top RPMs @50 Hz is 11400 which is well within the ~12000 RPM limit for the wheel
At top speed it's fairly humming along but most of the noise appears to be coming from the wheel scraping the slot ion the table - after a while this should open up slightly and quieten down.
The grinder is of course on a VFD so I can go higher but I will limit this grinder to 50Hz
When the thin kerf cutting cutting wheel was in the small table saw it was only running at 3000 rpm which was sort of a lot safer, and a LOT quieter, and not that much slower than an angle grinder
BUT
it used up more wheel and hence generated a more wheel dust per mm of cut. This is a well known effect and that is why these wheels are run at higher speeds.
These wheels are cheap so I am not worried about the cost but I would like to make less wheel grit/dust wherever possible.
However there are an advantages of being abel to run at slower speed and that is one had better control of the cutting.
Overall I'm pretty happy with how it has turned out - it has taken me ages to do all this but I did not have to make any part more than once (that's rare for me) and all the steel (even the SS) was bought at scrap prices or were laying around in my stash. The pieces of SS were a real find - I have 4 more pieces like the one the table is made of.
That's about all I can say for now and will have to play around with it and see what it can do at what RPMS etc.