should I buy this grinding attachment?

[liveaboard]

The add doesn't say much; and I know almost nothing about these things.
But it's not to far from me and the price seems reasonable at 150 Euros

[NP317]

Do you NEED a tool post grinder?
~RN

[liveaboard]

define "need"

[Harold_V]

A tool post grinder will enable one to grind items that may be difficult to turn with carbide, and will yield a better surface finish. They do not lend much towards precision (unlike a cylindrical grinder), although the improved surface finish and a wheel's ability to grind without tearing are a benefit.

Negative aspects of tool post grinders---

You risk damage to way surfaces as it's impossible to protect them from swarf. Precision grinders are built differently, such that swarf never sees such surfaces.

One must grind dry with a tool post grinder. That tends to be troublesome, as grinding creates heat. Heat expands the part being ground, so sizing can be difficult.

A tool post grinder is typically equipped with multiple pulleys, so the proper speed can be selected. It's easy to use the wrong combination, which can result in an exploding wheel. That can be lethal.

The grinder, as pictured, does not include a wheel guard. It would be foolish to operate the grinder in that configuration. If you feel you "need" that grinder, make sure a wheel guard is included. Also, ensure that an internal spindle is part of the bargain.

H

[SteveHGraham]

Of course you should buy it! Wait...let me see what it is.

In all seriousness, even with my limited skills, I am aware that people find these useful for grinding tapers and truing up chuck jaws.

[spro]

Something else. Consider mounting it to the lathe compound. Generally the motor is at the back and the wheel is toward the headstock/chuck/etc. Some TP grinders have a different mount so the motor is suspended above the wheel arbor. This one appears to have a base that would place the motor right over the cross slide handle, when the wheel is towards the chuck.

[jcfx]

How big is your lathe ? A TP Grinder should be sized to your lathe.
That TP Grinder looks pretty big compared to the feet in the last picture, unless the grinder is on a table
and it's a illusion.

[liveaboard]

Thanks everyone;
I don't know how big it is; the ad says nothing except that he's selling it for a friend who doesn't use it.

My lathe is pretty small [11" max working diameter] so it might be too big to mount usefully. Most lathes here seem to be big things for agricultural machine repair and such.

Harold makes some good points [as usual]; I had assumed the grinder would improve accuracy. Thanks for setting me straight.

It will take me a half day to find the location and see the thing [GPS systems can't find Portuguese addresses]. Maybe I'll let it pass.

[spro]

Liveaboard It is always good to communicate with you. If we look at this grinder, it appears it may be universal in some way. See the arbor/quill unit looks to be clamped into the base- I could be wrong but lets go with that a minute. If that was reversed and the motor was reversed, the motor would sit at the back and the grinding wheel towards the chuck. You have a shroud or could make an adjustable one.
The Main Two things are the condition of those bearings and whether there is another shaft or that one is also dual duty. It's possible, that a tapered plug is removed for a collet or the wheel thread accepts a small chuck....anyway the beauty of these is hi speed internal grinding. Like Harold said, its a deal breaker if that can't be accurately obtained.

[liveaboard]

Three photos were posted with the ad [2 of which are upside down]. I'm sure there is no more of it.
It looks pretty old. look at that small flat belt.
The motor is 3-phase yet only 1/2 HP.
There's an odd appendage above the spindle; a bearing adjustment [would indicate plain bearings]?
Like I said, I know almost nothing about these things. I'm a self taught lathe novice who tends to shoot a bit high.

[John Evans]

All toolpost grinders that I have ever come across use flat belts! That is commercially made units,not home made.But, yes I would say too big for your lathe anyway give the motor power. 1/4 HP would be what I would expect to see on a suitable grinder for your lathe.

[pete]

Yep Johns right about those flat belts. All the commercial units I've seen use them. My guess is there used because it's easier in some way to make or join smooth running flat belts than it is with the more normal V belts. And plain bearings are still used today on some of the worlds most accurate lathes. Kept within there operating range and well lubricated there more rigid and accurate than any ball or roller bearing made today. Those bearings would be the first thing I'd be checking if I was looking into buying it. Tough to estimate sizes from a picture, but going by the wood grain and board size on that pallet I'm guessing that was meant for at least a 18" swing lathe. (maybe) Some manufacturers didn't seem to offer the extended internal grinding spindles so that one may not have either. Going by the new prices for those additional spindles there more than pricey for the ones that do make them. If your really wanting a tool post grinder that would fit your lathe for a semi reasonable price Hemingway Kits in the UK sell a for a shop built one that looks pretty good. It's still 420 British pounds though.