6" cut-off wheel in a bench grinder

I have to cut 2 perfectly matching slots in a 5 mm thick flat semicircular piece of steel, each 15 mm by 5mm. As per suggestion on another thread I doubled up on the hacksaw blades. This
gave me only just over 2 mm. Cutting this length with a file is not a prospect I relish. I tried with a 3/32 cut-off wheel in a 4-1/2" grinder. This works but holding the grinder in exactly right plane is tricky.
I wondered: what if I put a 6" cut off wheel into my bench grinder. I would have access and control. Even if the wheel produced a thinner slot, one could control two passes this way more easily than with a hand-held grinder.
Is anything like this feasible? has anyone done this? The maximum speed for the 6" cut-off wheels easily exceed the 3,500 rpm of the grinder. At this point I cannot see any other safety issues beyond those related to using a bench grinder in the normal fashion.
Failing this, what is the maximum number of hacksaw blades anyone tried cutting with at once?
--
Michael Koblic,
Campbell River, BC
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Put two cut off wheels tight together = wider slot...
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Michael Koblic wrote:

Go get one of the cheap tile saws that use a 4 1/2" grinder as the power source. Replace the diamond blade with a cutoff wheel. Now you have a flat table with built in cooling, the guide rails will steady the grinder and give you a 90 degree cut.
I have one here that I used for a long time.
--
Steve W.

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Really? That is interesting! It could solve all kinds of other problems for me. Canadian Tire have a small tile saw on sale from time to time for $50.
So you did not have any problems with the plastic melting? And you used standard 4-1/2" cut-off wheels with the water bath? I just had a look at the Dewalt tile saw manual. They warn strenuously against doing just that...BTW, what is the rpm on the tile saw - same as an angle grinder?
--
Michael Koblic,
Campbell River, BC
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Michael Koblic wrote:

Nope, no problem as long as I kept the water flowing. I would bet the plastic would melt without coolant. Don't try to cut the notches all in one pass and let the part cool down a bit and it would reduce the risk to about zero.
I can't imagine why a company that also make metal cutting tools would tell you not to buy a cheaper tool to do the same job ;-)
The tile saw I have uses the same grinder that I use for normal use, it does have a rubber sleeve that keep water out but other than that it's the same design.
--
Steve W.

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Ha! The economics of tools is something I only started appreciating the last two years. Canadian Tire is very funny like that. They have obviously acquired a boat load of various tools they have difficulty shifting. Even heavy discounts (4-1/2" angle grinder for less than $20) do not seem to help. Then they start inventing all kinds of gimmicks to sell the stuff - in the case of the said grinder they made a stand for it to make it into a quasi-chop saw. I doubt that they sold many.
They have produced a "cutting tool" which is like nothing else. It also does not sell as judging by the on-going discounts. I had a look at it - it was quite useless!
There are quite a few other examples.
I sort of looked at the tile saw last time it went on sale (I was cutting stones at one stage) but dismissed it as my grinder did the same job with a diamond blade - dry!
To be fair, they do sell some very good stuff and they have a liberal return policy.
Thanks for the tip.
--
Michael Koblic,
Campbell River, BC
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Michael Koblic wrote:

I have a version of the mini chop saw mounted on the end of the bench. It's handy for cutting off bolts and all thread type stuff.
You get a square cut and less time gets spent chasing after the small pieces you just cut off and sent flying into that pile of oily rags!!!
--
Steve W.

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On Wed, 28 May 2008 23:17:45 -0700, "Michael Koblic"

Usta be, back some 50 years, you went to CTC to buy car/bike parts; then they added fishing tackle. Now they have so many gim-cracks and gew-gaws, they had to open Partsource to sell anything to do with automobiles, and the last time I was THERE (because TSC was moving and had sold out of 3/8" gas line hose and second son was stranded) THEY wanted 5xprice for a piece. Anybody want a collection of "funny munny" cause I don't go there no mo! Gerry :-)} London, Canada
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That would ruin a good part of my social life!
Here the choices are: 1) CT 2) House of Tools - you have to pick and choose. I am still waiting for two $5 clamps 2 moths later. OTOH, they are the cheapest suppliers of threadlockers. YMMV 3) Home Hardware - excellent for fasteners, forget everything else 4) Rona - forget it! 5) Acklands-Grainger - OK if you are a Company and loaded
or, after 46 km drive
5) Home Depot 6) Midland tools - odd shop that. Stock seems endless but when you look for specifics they seem to be "just out". Good prices though.
--
Michael Koblic,
Campbell River, BC
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"perfectly matching slots" cut by hand???
Try a dish wheel in your angle grinder to gouge out most of the slot, otherwise this is a job for cold chisels. Use a "cape" chisel to cut narrow slots on the sides and a regular cold chisel to remove the center. You still need good eye protection but this is a lot safer than watching the line closely in a shower of sparks.
Grind the teeth off one edge of a file to make it cut sharp inside corners and only work one surface at a time. Coarse files are better for long cuts because the teeth don't fill with chips halfway through the stroke.
The real answer is to pull yourself out of the 18th century and get adequate machine tools. The skill to do good work by hand takes a long apprenticeship to acquire but has almost no commercial value any more, unless you are an artist. What's your time worth?
I picked auctions and second-hand dealers as my best time-vs-money tradeoff. Even very old machines can cut metal more quickly and accurately than I ever could by hand. My time is spent fixing/ restoring them and sharpening cutters. Almost everything I own was broken when bought and still has problems but they work well enough most of the time. When I'm stopped by one of their problems I fix it.
I think the minimum satisfactory home or experimental shop equipment is a mill-drill or small vertical knee mill and a 9" - 12" lathe. Smaller machines are OK to make models but not for equipment that does useful work.
I have a Clausing vertical mill, a 10" South Bend lathe, a 4X6 bandsaw and don't see the need for anything larger, and I built a log splitter, a sawmill, and bucket loader for my garden tractor with them. I could put up with a mill-drill for most projects.
A small horizontal mill could substitute if you get a good deal but then you need a better drill press, and new cutters are much more expensive than end mills.
Jim Wilkins
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Good post, Jim. I would bet your equipment consist mirrors about 90% of most RCMers.
Bob Swinney
wrote:

"perfectly matching slots" cut by hand???
Try a dish wheel in your angle grinder to gouge out most of the slot, otherwise this is a job for cold chisels. Use a "cape" chisel to cut narrow slots on the sides and a regular cold chisel to remove the center. You still need good eye protection but this is a lot safer than watching the line closely in a shower of sparks.
Grind the teeth off one edge of a file to make it cut sharp inside corners and only work one surface at a time. Coarse files are better for long cuts because the teeth don't fill with chips halfway through the stroke.
The real answer is to pull yourself out of the 18th century and get adequate machine tools. The skill to do good work by hand takes a long apprenticeship to acquire but has almost no commercial value any more, unless you are an artist. What's your time worth?
I picked auctions and second-hand dealers as my best time-vs-money tradeoff. Even very old machines can cut metal more quickly and accurately than I ever could by hand. My time is spent fixing/ restoring them and sharpening cutters. Almost everything I own was broken when bought and still has problems but they work well enough most of the time. When I'm stopped by one of their problems I fix it.
I think the minimum satisfactory home or experimental shop equipment is a mill-drill or small vertical knee mill and a 9" - 12" lathe. Smaller machines are OK to make models but not for equipment that does useful work.
I have a Clausing vertical mill, a 10" South Bend lathe, a 4X6 bandsaw and don't see the need for anything larger, and I built a log splitter, a sawmill, and bucket loader for my garden tractor with them. I could put up with a mill-drill for most projects.
A small horizontal mill could substitute if you get a good deal but then you need a better drill press, and new cutters are much more expensive than end mills.
Jim Wilkins
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I think it's typical of what we settle on after struggling to work metal by hand, then buy undersized, inadequate machines because the good ones look so shockingly expensive. I bought a 6" Sears lathe first, and tried milling on it and a drill press. An adequate lathe or mill doesn't really cost more than a motorboat, ATV, snowmobile or HDTV and they hold their value much better. At least that's my excuse, they are "investments".
Michael, that's where you may be headed.
Jim Wilkins
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I see I managed to filter off Jim's post inadvertently, so I guess I have to respond "second-hand".

***Perfection in this case being in the eye of the beholder...

***Never thought of chisels. Will they work on 5mm thick plate?

***See, this is the sort of thing I would not have thought of and that makes perfect sense

***I am hoping to join the 18th century sometimes next year. The time value - at present little. That may change.

I am sure you are right. I am in fact looking. The 9-12" in the lathe department would be the swing-over-bed? There is a slew of small lathes on the EBay, 7"x 8-12", all under $600. The bigger machines are out of my league. The other issue is space.
--
Michael Koblic,
Campbell River, BC
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Mild steel plate? Sure, as long as you clamp it solidly to something heavy. You can practice on wood across the grain to get the feel to cut a constant depth. Chisels are "Armstrong Milling Machines". The last steel I chiseled was rivet heads on a truck frame, the last wood was a new transom I fitted onto a neighbor's boat last week. In neither case did machine tools help. It's a useful skill.

You can buy files with a safe edge for finishing inside corners. The common types are "hand" and "pillar". I use them a lot for custom cutouts in electronic control panels.

This crazy guy is a good source of technical books from the early 20th century, which is about the state of the art for many of our home shops today. He has had a better selection in the past but Elements of Machine Work and Advanced Machine Work are good.
http://www.lindsaybks.com/

US practice is to specify a lathe by maximum work diameter over the ways and length of bed. My 10" x 42" lathe can hold a 10" pulley blank on a face plate but it's limited to stock a bit less than 6" diameter over the carriage and about 20" long.
If I had the space I'd own a Bridgeport. I passed up a Monarch 10EE for $2000 because I had no room for it.
Jim Wilkins
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Know anyone with a surface grinder? Dress the wheel to 5mm far enough to do the slot. Carbide em in a bridgeport. I'm assuming this is something fairly hard.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
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