Slow speed grinder

[Bob Willson]

Ever since the Toowoomba GTG of the WWF mob I have been scheming ways to get a slow speed grinder.
A few days ago I realised that I already have most of what is required in the way of the slow speed stuff, all I needed was a work head (Carbatec catalog p56) a V belt, and a lathe, and I could make the rest of it from scrap.
I have a lathe. :) The lathe has many speeds. :) All I need is a way to harness that power and speed. Enter the mysterious realm of thought processes or what passes for them in my case.

If I hang a work head, mounted on a platform of some kind, off the side of the lathe all I need to do is put a pulley on a spindle, attach it to the work head via a V belt and run it all from the lathe chuck. I would then have all the slowosity (Pat. Pend.) I need. If the lathe is turning the wrong way then to fix this I only need to put a half twist in the V belt. The weight of the power head, the stone and its mounting frame would be enough to allow it to hang freely off the side of the lathe with just two pegs (head cut off bolts) to keep it all level. The only mod to the lathe would be two small holes about 8mm dia to be drilled on the lathe bed to locate the two positioning pegs.
All very simple, cheap and effective. I am a genius. :D

[Wood Butcher]

Well hurry up and build the thing so we can see some pictures!:P

Actually sounds like a good idea Bob, hope it works well!

[Ramps]

Hate to be a piker but I thought of something similar but the powerhead was a geared down washing machine motor that I was running on a spindle already.

I went and looked at the prices of all the other bits (extra pulleys, belt and the real expense the stone) that I needed and then was trying to design a waterbath that I could run it in...

Came home with a GMC one from bunnies at just over a hundred bucks ... haven't looked back (after truing up the wheel :o )

Anyway sounds like the fun of it that keeps us all going so have a go and give us a show:D

[Bob Willson]

Hi Ramps
I also bought a GMC one except that I got it for $40 on special. :) The problem with the GMC is that it is too fast for grinding HSS without burning. the steel. What we found was needed (and as demonstrated by Toolin Around) was a sssllllloooow speed grinder running at about 40 RPM. At this speed, it is very difficult to burn the steel, but the stock is still removed quite quickly enough.

Being a bit of a cheapskate myself (although not in Biting Midge's class) I am now looking for a cheap work head with a 5/8" shaft. The Carbatec one is a bit pricey but I will buy it if I have to. :(

PS Tooling assures us that he uses the cheapest (crappiest?) wheel that he could find for his set up; In his hands it all works brilliantly.

[Ramps]

Hi Ramps
I also bought a GMC one except that I got it for $40 on special. :) The problem with the GMC is that it is too fast for grinding HSS without burning. the steel. What we found was needed (and as demonstrated by Toolin Around) was a sssllllloooow speed grinder running at about 40 RPM. At this speed, it is very difficult to burn the steel, but the stock is still removed quite quickly enough.


##@@$%!! :mad:
Ripped off again $40???

Still at $100 I found it worth the $$. I haven't been able to burn anything with mine ... you know the black placcy thing onder the wheel? Well it's meant to filled with water :p

Must be that I just have cheap steel in all my planes and chisels ... wouldn't surprise me as I couldn't quite the extra $80 for the HNT Gordon plane to get the HSS and I don't know what Lie Nelson put in their planes? For a scrooge you must spend a bit on your tools to get HSS :)

All the best I'll be interested in your creation.

[bitingmidge]

Being a bit of a cheapskate myself (although not in Biting Midge's class)
Hey Bob! It costs a lot of money to look this cheap!

I have thought of doing similar using an el-cheapo drill press, but now that I think of it, I actually have a few (three) old variable speed 12v battery drills hanging round with no batteries that people have given me because I can't bear to see them thrown out. IF I hook them up through a 12v transformer (or a phone charger even if I can find one with enough current capacity), I could just make a series of slow wheels!!

There's no load on the things, so it shouldn't matter if they are down on torque.

Maaaate!! Thanks Bob, I may just give that a go!

Cheers,

P :D :D :D

[savage]

The weight of the power head, the stone and its mounting frame would be enough to allow it to hang freely off the side of the lathe with just two pegs (head cut off bolts) to keep it all level. I am a genius. :D

Hi Bob, just a note on your design, as I have powered a wood lathe in a similar fashion in that the motor was hinged as your powerhead is to be. The thing I found was at certain speeds it would start to bounce not unlike a wheel out of balance, so to rectify this I attached an extension spring to keep tension on the motor, in your case the powerhead.

[Toolin Around]

Ever since the Toowoomba GTG of the WWF mob I have been scheming ways to get a slow speed grinder.
A few days ago I realised that I already have most of what is required in the way of the slow speed stuff, all I needed was a work head (Carbatec catalog p56) a V belt, and a lathe, and I could make the rest of it from scrap.
I have a lathe. :) The lathe has many speeds. :) All I need is a way to harness that power and speed. Enter the mysterious realm of thought processes or what passes for them in my case.

If I hang a work head, mounted on a platform of some kind, off the side of the lathe all I need to do is put a pulley on a spindle, attach it to the work head via a V belt and run it all from the lathe chuck. I would then have all the slowosity (Pat. Pend.) I need. If the lathe is turning the wrong way then to fix this I only need to put a half twist in the V belt. The weight of the power head, the stone and its mounting frame would be enough to allow it to hang freely off the side of the lathe with just two pegs (head cut off bolts) to keep it all level. The only mod to the lathe would be two small holes about 8mm dia to be drilled on the lathe bed to locate the two positioning pegs.
All very simple, cheap and effective. I am a genius. :D


Lee Valley offers another one that I brought to the demo http://www.leevalley.com/wood/page.aspx?c=2&p=32960&cat=1,43072,45939 I like this one cause it can take a 4 step pulley and mounts two wheels (you can have a grinding wheel and a buffing wheel mounted together). It's only draw back is you have to align the bearings well or they burn out quickly.

[Bob Willson]

I have ordered one from Canada. If they follow their normal excellent practices then I should get it by yesterday ... or sooner. :)

[Bob Willson]

Cancelled the order on the Canadian stuff. The postage would have been:

*Surface Mail 8-12 Weeks $34.13
*Xpress Post 6-10 Business Days $59.66
*UPS Express 5-6 Days to Major Centers $71.87

I will just have to bite the bullet and buy the Carbatec one unless somebody knows of an alternative (cheaper) source.

[bitingmidge]

Bob,

I've been thinking more on my drill thing. They are all Ryobi 7.2v Batteries are P72A's which can be bought for around $50.00

I haven't a clue how to make them go directly from a transformer, but can anyone tell me why they won't work to drive a grinding wheel? It would be easy enough to clamp them in one spot.

Cheers,

P

[JDarvall]

Just an opinion Bob, but I don't think you need a slow speed grinder.

I played with the idea plenty. I made my own grinder setups using workheads and washing machine motors.....had the pulleys set for a slower speed and have since realised its not necessary. I've sped them all back up to around 3000rpm, by changing pulleys over.

You can monitor the heat buildup reliably using your fingers close to the edge. You can still burn a blade if you don't monitor this heat regardless of the speed.

I believe just dress the wheel frequently, use a ALO wheel and fingers close and she'll be right.

But having said that I don't want to be a killjoy Bob (probably too late !). Sounds like it an interesting thought for you.

I've got that blue carpatec workhead (5/8") and it works well though, if thats any help. Being going strong 5 or so years now. The only grip I have is thats its only threaded one end to hold just a single wheel. If anybody finds an affordable double mount workhead for sale I'd appreciate the headsup.

[Bob Willson]

Bob,

I've been thinking more on my drill thing. They are all Ryobi 7.2v Batteries are P72A's which can be bought for around $50.00

I haven't a clue how to make them go directly from a transformer, but can anyone tell me why they won't work to drive a grinding wheel? It would be easy enough to clamp them in one spot.

Cheers,

P

Very easy to make them work from a small transformer pack Peter. Just find the bit where the batteries connect their positive and negative outputs to the drill and solder on the transformer leads instead. The only things you need to be careful of are:
Transformer has sufficient power (amps)
Transformer puts out correct voltage
Transformer puts out rectified voltage (DC not AC)
Connect the positive lead to the positive terminal. A simple test with a ohmeter will determine the output of the transformer.
Apart from that it is really all very easy to do. I have modified several of my old battery powered thingys in this way. If you are feeling a bit advetturous you may even like to bump up the voltage to get a better power output. Not (generally speaking) a good idea, but is OK for some (intermittent) uses

[pfred1]

Transformers are AC devices. Although wall wart, battery adapters do contain diodes in them to rectify the voltage into DC. I have taken a few of these devices apart and have not found any of them to be very robustly built. Most seem to be in the 500 milliamp range as I can recall. That would be a whopping 3.6 watts at the stated voltage. Can we say weaker than a nite lite?

You can run a tool off one of these things? It sounds like a recipie to burn your house down to me. I was going to post a different reply about making a power supply but it got a bit more complicated than most people could follow unfortunately. If anyone is really interested in making DC power supplies contact me and let me know, I've built quite a few of them.

[pfred1]

HOMEMADE TOOLS AND JIGS ETC. Got a homemade tool or jig you want to show off? Here's your chance. Show us what you've got.
OK here goes a wet diamond grinder I made out of scraps I dug out around the yard once:

http://home.comcast.net/~pcf1/p7160002.jpg

I have been on a bit of a grinder making kick lately after I bought a milk crate full of different grinding wheels for $10 at a flea market last summer. When I get around to it I'll take some pics of some of the machines I've made lately and post them here too.

[bobsreturn2003]

made one years ago as i was trying to sharpen bowl gouges and they kept getting eaten .while i made up my mind how to sharpen them with the grinder on . used an old arbour ,and 1440 rpm motor with a v pulley ran about 5-600 rpm had the pulleys. and use a white wheel . works great for sharpening . high speed grinders are best for shaping , also have a tormek great for honing . and diamond files for touching up when turning . has taken some timeand experiments to work out what works for me . please be carefull with the open type motors as they can bite , dont have photos just an old drill press motor and arbour bolted to a piece of pine with slots to tension .:B :B

[woden]

Bob, did you find that 1440 rpm was fast enough to burn edges easily? And was that just with HSS turning tools or could that speed easily burn high carbon steel as well? I've been looking at a medium speed grinder of about 1400 rpm and am a bit concerned that being such a klutz at times that I'll reck a load of tools using it. I want something for removing nicks and major reshaping, the honing bit I do on wet/dry.

[Toolin Around]

Bob, did you find that 1440 rpm was fast enough to burn edges easily? And was that just with HSS turning tools or could that speed easily burn high carbon steel as well? I've been looking at a medium speed grinder of about 1400 rpm and am a bit concerned that being such a klutz at times that I'll reck a load of tools using it. I want something for removing nicks and major reshaping, the honing bit I do on wet/dry.

Everyone is clumsy at first but you will get better. That speed is about half the normal speed so you can still over heat anything if you're not careful. What the lower rpm will do is allow you a bit more time at the wheel. That way you can take a bit more time thinking about what you're doing.

[pfred1]

Bob, did you find that 1440 rpm was fast enough to burn edges easily? And was that just with HSS turning tools or could that speed easily burn high carbon steel as well? I've been looking at a medium speed grinder of about 1400 rpm and am a bit concerned that being such a klutz at times that I'll reck a load of tools using it. I want something for removing nicks and major reshaping, the honing bit I do on wet/dry.

RPMs is not what burns tools up SFPM (Surface Feet Per Minute) and wheel structure are the culprits here. When you are looking for that grinder pay some attention to the wheel that you mount on it too. Medium grit gray aluminum oxide wheels will burn tools much faster than an open grained, fracturing, white, or pink wheels will.

That, and loaded up wheels are pretty bad news too. If a wheel is cutting, as opposed to just rubbing, the chance of burning the tool up is much less. I don't let my grinding wheels accumulate any glaze, or become dull. I dress my wheels often. For wheel dressing I use industrial diamonds. Some people use those star dressers, but I don't care for them myself.

Echoing apricotripper's earlier post in this thread,

"You can monitor the heat buildup reliably using your fingers close to the edge. You can still burn a blade if you don't monitor this heat regardless of the speed."