Thread: Bench grider for razors

Definitley need to slow down a bench grinder below 1800 RPM.
I'm still experimenting with this with no luck yet, dimmers, pulleys etc, I',m cheap can't afford a VFD. It's ok for thinning blade before heat treat but after as the blade gets real thin you will wreck the blade in a cold second if it heats to the point of turning the blade a dark brown/blue or purple color.
Also a coolant would have to flood the blade to be on the safe side. Water and electrics ain't a good combination - Bob Allman put me right on this.

Be safe

Joey

A bench grinder can be slowed down by fitting a small pulley to it and using a larger pulley on a separate spindle - the spindle takes the pigtail end that fits the mops. A 'v' belt connects the two together.

Rheostats will not work on all types of grinder - depends on the type of motor, brush/brushless, induction... When it does work, unless you use a VFD (variable frequency drive - expensive) the rheostat will only reduce the voltage to the motor, not the amperage, so the motor will run hotter and burn out quicker. Not something to be overly worried about if you are using a cheap motor for short bursts, but worth pointing out for anything expensive.

Regards,
Neil

I believe my buffer/grinder is a Delta. It has a Rheostat built in that allows me to slow it to 1725 rpms. Perfect for buffing....

Something like this: Multitool belt and disc grinder attachment at Van Sant Enterprises, Inc.

Or: Caswell Inc. - Expander Sanding Wheel

Or: Cone Loc Drum Sander for Shop Rolls American Jewelry Supply Rolls

No matter which one of these you pick, solve the problem that rpms will give you. The slower the better, variable speed if possible.

I have a top of the line kmg clone grinder for knife grinding and what ever. I will be making razors soon . And just got my hands on a few blades to learn measurements. Making a razor blade wont be really easy with any of the machines you guys are looking at and might end up costing yo a fortune in belts as they are not cheap. Im thinking I should be able to make a razor blade in under 3 hours then a handle pending material in another 3 . The heat treat shoud be fairly easy with most razors being tool steel. They grind alot easier and are way softer than what I normally do knives . I use cpm154 about 3 times tuffer than any tool steel. I have lots of L6 and will try that first Ill try next week making a few . I gotta finish up 8 knives then my table is clear .If you guys want to see some nice grinders go to the knife forums. knifedogs.com or bladeforums.com

Thanks. I like the look of those expanding sanding wheels.

For making a razor from scratch? From a piece of flat stock that is annealed?

If so then in theory yes but only up to a point. Do not use soft wheels, your trying to make a concave grind, not a flat grind. The higher speed is ok for roughing out, then drop to the 1750 to finish the rough concave grind. For finish grinding after heat treating and tempering you will need a much slower speed because it is so easy to burn the steel. Reduce to a speed of no more than 850 rpm or even half of that for final, final work on the blade.

Hope this helps,

The more I grind, the slower my belt speeds get. Lately I have been using the pulley set-up that gives me about 550 ft/min most of the time.

I used a geared down (with pulleys) grinder to make a few razors it worked fine.

What I used to think was slow, is now fast. (or it could just be my brain function is slowing )

Charlie

i have a KMG with 2HP and a VFD
i too start fast and then slow the grinder as i get farther along

the double wheel grinder would best be set up with gator belts at the end (sept you cant run them wet ) they were ment for CNC grinders and are all the same thickness no matter the grit (A300-A30) they also can be dressed like a grinding wheel and leave a nice smooth finish (these ar my fav finishing belts )

also you would need more then a handle ful l of wheel sizes for the different grinds (price out that once)

the expanding drum sanding deals are good but have a hump in the middle from the compression (you jsut have to learn how to deal with that ) they also are limited in grits that you can get

The original problem was converting a bench grinder (presumed hard stone wheel) to one more friendly to making razors.

The most general rule for beginners should be to buy tooling that works and is cheap. Lots of early blades for most makers will be made on a lot simpler tooling than what they can afford in later years. And those tools will be full of quirks that have necessitate adaptation, as Lloyd says "the humps." Or their production requirements will increase the quality and quantity of tools. Use what you have now, until you can afford or need something better.

The older simpler stuff forces you to figure out how the process works and what needs to be done to remove everything that isn't shaped like a razor. Better tooling makes things more efficient. If you don't understand the basic processes, better tools will not make better blades.

Even old tools that have adjustment for belt or wheel speed will be more helpful than one that is not adjustable (variable speed).