Thread: Circle cutter/donut spur/ nicker

JK, if you cant find the spurs you can always try to make one although I realize they are very small, but it would be quite challenging. I've made a couple of small (16mm diam) circular cutters from blue steel scraping blades ($7 at Bunnings). Its quite hard stuff to cut but it can be done. I start by marking out the required circle size on the scraper blade and then drill the required centre hole. You'll need a fair bit of pressure and lube but eventually you'll get though it. Then I used a metal cutting blade to roughly cut the outer shape about 1-2mm oversize. use a long bolt through the hole as a holder and then insert into either a lathe/DP and use a file to get it circular and also put the bevel on it. An alternative is to put the bolt in a hand drill and place the whirling blade to be up against a grinding wheel or belt sander, this method is much faster but you can stuff it up and get it out of round easily.

While you are at it you can make 3-4 (you can put them all on the same bolt for basic shaping) so that you have some on hand if you lose one.

Cheers

Bob

thanks for the thought! (I think)

A few questions:

1. What is the thickness of the scraper blade you used?
2. Do you think that a cabinet scraper blade would do as well?
3. Should I anneal and temper it?
4. When you say you used a metal cutting blade, what tool did you used that in to cut the outside circumference?

Cheers

Jeremy

1. What is the thickness of the scraper blade you used?
   I think it was 0.08"?
   
2. Do you think that a cabinet scraper blade would do as well?
   Yep!
   
3. Should I anneal and temper it?
   No, it should not be necessary unless you over heat it while shaping it. The biggest problem for you will be drilling the hole. You will need plenty of lube,coolant. Standard scraper blades are about the same hardness as most ww blades. I've measured about a dozen scraper blades and they range in RC hardness 49 to 58 with most being between 54 and 56. Last year I bought a whole lot of blades from stores and tested their hardness at work and then returned all the ones that were below 54. The testing leaves a tiny pinprick that can barely be seen on the surface of the metal. The blue steel scrapers are from memory RC56? This would be fine for a spur or nicker.
   
4. When you say you used a metal cutting blade, what tool did you used that in to cut the outside circumference?

Ah yes, I have a 115mm diam 1.6mm kerf metal cutting blade in an old baby (8") table saw that runs at 2800 rpm and enables me to make small fine cuts. An angle grinder (10,000 rpm) would need to be used judisciouly to do the same thing as it could destroy the temper notto mention other things. A Dremmel tool with a metal cutting blade might be the way to go. The dremmel kerf is even finer and you could hold your fingers near the balde and if it gets too hot, just pause or cool it off in water.

Hope that helps.

Thanks

I will see how I go.