- Joined
- Nov 16, 2012
- Messages
- 5,596
Call me old fashioned but, anytime two gear teeth come into contact, they create a pulsing force thats called vibration.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
B
British Steel
Forum Guest
Register Today
Mike, I.couldn't agree more... Unfortunately a lot of.machines (particularly from the Chinese mainland) are built with as.much care as that backplate's threaded 
A good quality lathe can definitely cope with steel chucks, mine has an all-steel Pratt-Burnerd and there are no vibration issues - then again, I can balance a 2p on edge on the headstock while starting and stopping at 1500 rpm....
Re the OP's backplate, It looks as though the casting either had inclusions (loose sand in the mould, par for the course in Chinese practice) or the.core for the threaded hole was.oversize and didn't leave enough meat for the threads.to be cut. Either way, it's an appalling example of quality control, and I'd be.sending it straight back for a refund. Not a replacement, which could be worse - although a complaint might get a rare good example picked like a.needle from a haystack!
Having been unfortunate.enough to have.worked for one of the UK's well known importers of Chinese Machinery I'm well aware that quality control, both.at the.manufacturers and the importers, isn't anywhere near the top of their priorities.... The only way standards are.going to rise is if the paying customers make a fuss and demand usable tools from 'em -.at the moment.there's the (arrogant) belief that the customer is always wrong where quality is concerned, although the first QC will be done by the customer!
A good quality lathe can definitely cope with steel chucks, mine has an all-steel Pratt-Burnerd and there are no vibration issues - then again, I can balance a 2p on edge on the headstock while starting and stopping at 1500 rpm....
Re the OP's backplate, It looks as though the casting either had inclusions (loose sand in the mould, par for the course in Chinese practice) or the.core for the threaded hole was.oversize and didn't leave enough meat for the threads.to be cut. Either way, it's an appalling example of quality control, and I'd be.sending it straight back for a refund. Not a replacement, which could be worse - although a complaint might get a rare good example picked like a.needle from a haystack!
Having been unfortunate.enough to have.worked for one of the UK's well known importers of Chinese Machinery I'm well aware that quality control, both.at the.manufacturers and the importers, isn't anywhere near the top of their priorities.... The only way standards are.going to rise is if the paying customers make a fuss and demand usable tools from 'em -.at the moment.there's the (arrogant) belief that the customer is always wrong where quality is concerned, although the first QC will be done by the customer!
- Joined
- Jan 11, 2013
- Messages
- 1,821
- Joined
- Nov 16, 2012
- Messages
- 5,596
A couple thoughts here as there are many views and different circumstances...
Quality control from Asia (and in this case, China) depends on the factory you deal with and amount of quality control you purchase when you contract to have the machines built. In many cases, yes, the customer is the first person doing quality control. -Usually when bottom of the barrel importers just buy the "house brand" line of equipment. Having been in the position of actually going to China to setup production lines for electronic equipment, I know how the game is played. If the importer pays for the QC, checks it when it arrives at the home warehouse and send back any rejects, the customer never gets a raw deal.
Vibration: Many of the older lathes (LeBlond and others) had various forms of "fluid drive" similar to an automatic transmission. These were all attempts at removing "gear noise". Even in those machines, gears were present in the drive train and they went to great lengths to make highly refined gears to reduce the inherent problems in all gears -which is impulsive vibration. Other systems used belts but, belts are at best 85% efficient. Monarch and Hardinge solved the problem but, it was not easy. Take a look at the parts diagram of one some time -quite a few gears in there and none of them (even by today's standards) could be made cheaply.
Virtually every machine in the past couple hundred years is/was made of cast iron -even though it would be easier and cheaper to make it from steel. Why? because whenever mechanical systems are at play, there will be vibration -and nothing kills vibration better than cast iron. And that's due to both it's density and crystalline structure. And by the way, the machine itself creates a small amount of the vibration compared to a bit digging into a piece of shaft or 4 flutes tearing into metal...
As it stands now, the gear systems in any half-decent Asian lathe are about as simplified as possible and the gear teeth angles are optimized to reduce vibration -all at an affordable price and in a package easy for a home user or light industrial environment to manage. And BTW: My lowly PM1236 can run at top speed and by hand, you can feel virtually no vibration. If the bench were bolted down and weighed 400lbs more, you'd feel none. Of course, putting the chuck and mounting a workpiece creates vibration. It can't be avoided -and that's why CI is used.
Ray
Quality control from Asia (and in this case, China) depends on the factory you deal with and amount of quality control you purchase when you contract to have the machines built. In many cases, yes, the customer is the first person doing quality control. -Usually when bottom of the barrel importers just buy the "house brand" line of equipment. Having been in the position of actually going to China to setup production lines for electronic equipment, I know how the game is played. If the importer pays for the QC, checks it when it arrives at the home warehouse and send back any rejects, the customer never gets a raw deal.
Vibration: Many of the older lathes (LeBlond and others) had various forms of "fluid drive" similar to an automatic transmission. These were all attempts at removing "gear noise". Even in those machines, gears were present in the drive train and they went to great lengths to make highly refined gears to reduce the inherent problems in all gears -which is impulsive vibration. Other systems used belts but, belts are at best 85% efficient. Monarch and Hardinge solved the problem but, it was not easy. Take a look at the parts diagram of one some time -quite a few gears in there and none of them (even by today's standards) could be made cheaply.
Virtually every machine in the past couple hundred years is/was made of cast iron -even though it would be easier and cheaper to make it from steel. Why? because whenever mechanical systems are at play, there will be vibration -and nothing kills vibration better than cast iron. And that's due to both it's density and crystalline structure. And by the way, the machine itself creates a small amount of the vibration compared to a bit digging into a piece of shaft or 4 flutes tearing into metal...
As it stands now, the gear systems in any half-decent Asian lathe are about as simplified as possible and the gear teeth angles are optimized to reduce vibration -all at an affordable price and in a package easy for a home user or light industrial environment to manage. And BTW: My lowly PM1236 can run at top speed and by hand, you can feel virtually no vibration. If the bench were bolted down and weighed 400lbs more, you'd feel none. Of course, putting the chuck and mounting a workpiece creates vibration. It can't be avoided -and that's why CI is used.
Ray
Mike, I.couldn't agree more... Unfortunately a lot of.machines (particularly from the Chinese mainland) are built with as.much care as that backplate's threaded
A good quality lathe can definitely cope with steel chucks, mine has an all-steel Pratt-Burnerd and there are no vibration issues - then again, I can balance a 2p on edge on the headstock while starting and stopping at 1500 rpm....
Re the OP's backplate, It looks as though the casting either had inclusions (loose sand in the mould, par for the course in Chinese practice) or the.core for the threaded hole was.oversize and didn't leave enough meat for the threads.to be cut. Either way, it's an appalling example of quality control, and I'd be.sending it straight back for a refund. Not a replacement, which could be worse - although a complaint might get a rare good example picked like a.needle from a haystack!
Having been unfortunate.enough to have.worked for one of the UK's well known importers of Chinese Machinery I'm well aware that quality control, both.at the.manufacturers and the importers, isn't anywhere near the top of their priorities.... The only way standards are.going to rise is if the paying customers make a fuss and demand usable tools from 'em -.at the moment.there's the (arrogant) belief that the customer is always wrong where quality is concerned, although the first QC will be done by the customer!
T
TOOLMASTER
Forum Guest
Register Today
looks like the metal just crumbled during threading....make you wonder if the plate will just snap at 3000 rpm
anyway.. they are sending another..HOPEFULLY BETTER
anyway.. they are sending another..HOPEFULLY BETTER
Last edited by a moderator:
- Joined
- Nov 16, 2012
- Messages
- 5,596
- Joined
- Jul 1, 2012
- Messages
- 1,356
We here in MN are lucky to have 2 excellent stores that sell used machine tool accessories. Polar Tool and Tried and True.
http://www.polar-tool.com/ http://fridley.patch.com/listings/tried-and-true-tools Next time you need something give them a call first as both are a great local source for tooling and inspection equipment. When I go in them I feel like a kid in a candy store, I can spend hours in them.. I have had 2 friends buy something from Shars and both were very dis-satisfied in what they received. You make 3. Rich
- Joined
- Jul 26, 2011
- Messages
- 4,142
Ray,I haven't bought cast iron blanks for several years. The last time I purchased any was about 10 years ago when Wholesale Tools were selling 6" blanks with a 1" hole for $15.00 each(I think). I bought 6 to bore out and fit the tapered nose of my Hardinge HLVH. I knew I'd never see them that cheap again. I've had no problems with the cast iron ones I have used. No hard spots,etc.. Even if you thread or bore your own,there can still be issues with the metal itself. I must be lucky.
I doubt that Wholesale Tools has access to better back plates than anyone else. It's just the luck of the draw. I've been to their Charlotte store,and wasn't too impressed.
As long as the cast iron itself isn't full of inclusions,hard spots,or some kind of crud,at least boring them yourself eliminates bad,careless threading.
The above face plate looks like the maker got impatient and tried to take too heavy cuts,fracturing the cast iron. Either that,or the material itself was faulty. I expect the threading technique was rushed and faulty.
I doubt that Wholesale Tools has access to better back plates than anyone else. It's just the luck of the draw. I've been to their Charlotte store,and wasn't too impressed.
As long as the cast iron itself isn't full of inclusions,hard spots,or some kind of crud,at least boring them yourself eliminates bad,careless threading.
The above face plate looks like the maker got impatient and tried to take too heavy cuts,fracturing the cast iron. Either that,or the material itself was faulty. I expect the threading technique was rushed and faulty.
- Joined
- Feb 22, 2012
- Messages
- 924
just to add to the 'vibration' case - I am not saying that the machine itself should generate vibration and the chuck to reduce it - the machine itself should be vibration minimized already. but when you chuck in a non concentric part in there, vibration will be induced no matter how great that machine was built.
- Joined
- Jul 1, 2012
- Messages
- 1,356
Take a pic of that one will you and let's compare... Did their customer service say anything about the bad one?
Rich