Gallery, Projects and General > Project Logs
Clock wheel cutter
bogstandard:
At a push, you can get away with a fine oilstone, they sell them on markets for a couple of squid, rough on one side, fine on the other. Forget about the side faces, you should flat the front face, the one that hits the work first, that should sharpen up all cutting edges. For lathe tools, you sharpen using the top face. It doesn't take long at all, you will soon see when the face has a chrome like finish, and you are liable to cut yourself on the edges. Then you know you have a sharp tool.
I actually use an Arkansas wetstone because it has a much finer grain structure than oilstones, and gives a super sharp cutting edge. Diamond laps can be used on HSS, and even with lots of water as lubrication, it will tend to clog up and ruin the lap. I keep those for putting a keen edge on carbide. Do not use the diamond laps with holes in, they are really useless for the size of tools we use.
Bogs
raynerd:
Just been looking at commerical cycloidal form wheel cutters, as Darren said although a cost it would allow me to concentrate on setup and relieve some of the issues with the cutter. I thought I only needed two cutters, 0.6 and 0.8 mod as these are the only ones mentioned in my plans. The cheapest I can find, including postage are P. P. Thornton and they are £52 per cutter for mod 1 and below!
Too much for me to spend on two cutters.
Then I researched into a little more and discovered that in actual fact, the cutters are for 20 teeth and over and I would also need an individial 0.8 and 0.6 cutters for the pinions as these are 10 leaf and below! It would cost £208 on cutters alone. I`m acutally going to convert the pinions to lantern pinions so I won`t need cutters for this but £104 is still too expensive for two cutters that will be used only a few times. I`m going to have to work on my profile of my cutter! It did do the job, I`ll try and make another I think and take my time.
I was quite excited when I noticed RDG sold cutters for £18.50 but then noticed they were involute cutters and not cyloidal ... since all books I have read discuss cyloidal I guess the involute system will not be suitable.
Chris
John Stevenson:
--- Quote from: craynerd on October 30, 2009, 01:03:21 PM ---
Tooth form looks quite good so far!
Look at the first tooth and how bent it is ... obviously it is the furthest one away from the current cut in the next photo:
Any thoughts.....?
--- End quote ---
In the first pic above the tool looks bent as if it bowed under hardening, may be the angle but if you didn't recheck centre then that will account for the leaning teeth.
In the second pic you don't have enough clearance on the cutter, not the brass smear marks behind the cutting edge, tool is nowhere near sharp enough.
If making silver steel cutters for brass or wood harden out to cherry read and quench, preferably water as oil isn't a sharp enough quench and the heat inside the cutter can cause it to temper at the same time as it transfers to the edge.
Then contrary to what you read don't temper. Brass and wood cutters can run at a higher hardness than ones for steel as it's a softer material.
The face grinding operation will actually put enough heat into the material to temper it slightly.
If you temper to what the books say the grind you actually reduce the temper, believe me brass and wood are far better at higher hardness's.
Wood is no good as a backing, far too soft, try alloy but remember to lubricate it with a drop of paraffin or WD40.
John S.
raynerd:
Cheers John, I`ve just this second come back in from cutting out two more blank wheel cutter disks. You are spot on, the wheel cutter seems to have bowed out - it is soft and not sharp and this was NOT silver steel. I have cut my new blanks from silver steel guage plate that was advertised as "suitable for hardening for tool steel". I`ve also done a little test, filed a little edge of a scrap piece then heated to cherry and quenched, then tried to re-file it. It was 100% significantly harder but my file could still dig in a little. Is this still right, even after hardening should I be able to file it a little, i.e make a mark? I don`t want to spend hours making a cutter and then find out that I can`t harden it again. How long do I need to hold the piece at cherry red before quenching?
I appreciate your advice regarding not needing to tempter the steel - I will try the cutter without tempring.
John Stevenson:
No once hardened a file should skid off it.
Get it bright red, hold it there for a couple of minutes and drop into a can of cold water and leave.
Then try that.
John S.
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