slow speed grinder ?

[cal thelen]

been looking at slow speed grinders woodcraft has one that runs at 1750 penn state has one that is two speed 3450 and 1750 lowes has a porter cable that i really like it is also 2 speed. but the lowest speed is 2000 rpm. is this slow enough for sharpening my gouges and skews ect? has anybody had any experience with the porter cable grinder pros and cons. any other suggestions/ thanks guys
cal

[Doug Herzberg]

Cal, Woodcraft has a no name 8" 1750 rpm grinder with two white wheels which is often on sale for around 100. The wheels which come with most grinders are probably not suitable for turning tools and good wheels will add a lot to your total cost. Don't know about the Porter Cable in particular. If you have a choice, go with an 8" grinder.

[Thom Sturgill]

If I understand correctly, Black and Decker owns the Porter Cable brand and did own the Delta brand. Since selling off Delta, I have noticed that Porter Cable seems to be filling the niche that Delta had, at least in the smaller (sub $1000) machines. I think it is possible that this is the same grinder that used to sell as a Delta grinder, in which case it is a good machine and I have had one for a couple of years. It looks VERY similar, except for the 'tool-less' nuts to hold on the wheels.

[Jamie Donaldson]

What makes the Woodcraft low speed grinder a hard to beat deal is the fact that it comes equipped with the Al Oxide(white) wheels already installed, and the other brands are most often equipped with gray wheels not well suited for HHS tools. Buying white wheels separately often costs more than the Woodcraft grinder.

[Harry Robinette]

The PC brand name has been sold to the Chinese and the product has turned into a nightmare because you don't know if it's like Thom said an old Delta or a new Chinese junk. Really look at the tools being sold in Lowes,HD or any box store under Porter Cable name and really look before you buy any.

[Jim Evans]

The PC brand name has been sold to the Chinese and the product has turned into a nightmare because you don't know if it's like Thom said an old Delta or a new Chinese junk. Really look at the tools being sold in Lowes,HD or any box store under Porter Cable name and really look before you buy any.

Porter cable is still owned by Stanley Black & Decker. They did sell the Delta brand.

[Joe Bradshaw]

Cal, I have the PC from Lowes and I fitted it with the D-Way CBN wheels and it works great.

[Robert Vroman]

I looked at the PC several years back, but ended up going with a Craftsman 8" variable speed. It was a little more, but it is 1725 - 3450 rpm as opposed to 2000 - 3400 rpm. It does come with one wire brush and one gray wheel though, so plan the expense of new wheels. Overall I have been very happy with it. As Doug said, 8" is the way to go if possible.

[Jon Murphy]

I agree with all previous posts. I've had the Woodcraft slow for over a year and find it quite adequate. I'd used a Jet slow/wet for years (10" wheel), and a high speed six inch for shaping. Space became a problem and I substituted the Woodcraft slow 8" for both. No matter which grinder you buy I suggest you get new wheels, although the white wheels on the Woodcraft are decent. I see no need for the dual speed, it really doesn't speed the reshaping of a tool as the higher speed means you have to take more time out to cool the tool. In the days of carbon steel tools the cooling could be instant by dipping them in water - but the HSS steels don't like the rapid cooling, it changes the crystaline structure of the edge (or so I'm told), so I see no reason for the higher speed on an 8" wheel. BTW, for those on 6" wheels, remember that the rpm of the shaft isn't the same as the speed of the wheel surface. The speed of the wheel surface on the tool is feet per second (or millimeters per second) - it is a linear measure. A wheel of a circumference of 3 inches (we'll use circumference rather than getting involved with Pi) spinning at 60 rpm has a linear speed of 3" per second. At the same 60 rpm a 6 inch circumference wheel has a linear speed of 6" per second. It is the linear speed that grinds the tool, and heats it - not the rpm.

Best, Jon

[Thom Sturgill]

I agree with all previous posts. I've had the Woodcraft slow for over a year and find it quite adequate. I'd used a Jet slow/wet for years (10" wheel), and a high speed six inch for shaping. Space became a problem and I substituted the Woodcraft slow 8" for both. No matter which grinder you buy I suggest you get new wheels, although the white wheels on the Woodcraft are decent. I see no need for the dual speed, it really doesn't speed the reshaping of a tool as the higher speed means you have to take more time out to cool the tool. In the days of carbon steel tools the cooling could be instant by dipping them in water - but the HSS steels don't like the rapid cooling, it changes the crystaline structure of the edge (or so I'm told), so I see no reason for the higher speed on an 8" wheel. BTW, for those on 6" wheels, remember that the rpm of the shaft isn't the same as the speed of the wheel surface. The speed of the wheel surface on the tool is feet per second (or millimeters per second) - it is a linear measure. A wheel of a circumference of 3 inches (we'll use circumference rather than getting involved with Pi) spinning at 60 rpm has a linear speed of 3" per second. At the same 60 rpm a 6 inch circumference wheel has a linear speed of 6" per second. It is the linear speed that grinds the tool, and heats it - not the rpm.

Best, Jon

Lets look at real numbers:
8" dia @ 1720 = 8 x 3.14 x 1720 = 43206 in/min --> That is almost 41 mph (multiply by 60/12 [or 5] to get ft/hr and then divide by 5280 to get mph)
For a quicker estimate 8 x 1720 / 337 is close enough.

8" dia @ 2000 -> 47mph - not too big a change, a little wear on the wheel will bring that down anyway
6" dia @ 1720 - reduce first number by 3/4 (6/8) --> 30 mph
6" @ 3440 - double that - 60mph

Not too many 6" low speed grinders are available, and at 50% faster than an 8" slow speed a HS grinder cuts too fast and generates too much heat.

My 8" dia wheel is now about 6" and my old 6" grinder has a wheel that's about 4 1/2" They don't work as well as they used too and the curvature of the hollow grind has visibly changed. About ready to move the old 8" wheel to the 6" grinder and replace it with a CBN wheel.

[cal thelen]

Thank you all for the information. Still undecided what i am going to do. wood craft is out of stock till end of november. If I decide on the porter cable and have to purchase two new wheels would I be best off getting 2 120 grit wheels or like the wc grinder comes with one 60 and one 120 grit?

[John Keeton]

Cal, if you are going to buy new wheels, bite the bullet and get the CBN wheels! You will never regret it.

[Steve Baumgartner]

If you get the Woodcraft one, ask the dealer to let you test run it before you take it home. Although the wheels that come on it are white, they are notorious for being out of round or out of flat, and it can take quite a bit of fiddling to get the grinder to run smoothly. When I bought mine, we went through three that wobbled terribly before I chose the best one, and it still needed tweaking the orientation of the flanges to take out the shimmies.

Steve

[Nate Davey]

I have the Woodcraft low speed with the CBN wheel. Absolutely worth every cent I paid for both items!

[Reed Gray]

Well, slow speed is fine, unless you want to do a lot of reshaping your tools. Once you have the profiles that you want, all you need to do is touch things up. There is a huge difference in my 1 hp Baldor grinder, and my 1 hp Woodcraft no name grinder motors, but both work.

If you are going to buy new grinding wheels for your grinder, CBN wheels (D Way Tools) is the way to go. You may spend more for the wheels, but you will not need the balancing system (not really necessary on most wheels), or dressing/truing/cleaning tools to go with them. They will probably outlast you, and run far smoother than any other wheel you will ever buy. You could get by with just the 180 grit wheel, but I have it and the 80 grit wheel.

robo hippy

[mark ravensdale]

Over here in the uk the most popular slow speed 6inch grinder seems to be the Creusen HP7500TS Powerline, now it ain't cheap but it's a good reliable well built grinder (should last a lifetime if shown a little respect!), not sure if it's available over in the US ?
I too would side with the CBN wheels they are great, I have a 6inch 100grit one they cut fast and cool and stay the same size, again they are not cheap but if treat with respect they should last a VERY loooonnngg time, worth every penny !!!