Mini rant - who drills the holes on these economy lathes?

[slow-poke]

I'm in the middle of replacing the cross feed lead screw with a ballscrew to reduce the backlash. To do so I need to fabricate various mounting blocks to replace the originals. You would think during the design of something like a lathe that if you needed 4 holes in a square pattern to retain say a block you wouldn't randomly choose 9.74mm, when 10mm would easily fit just as well. Further you would not expect to have one of the holes skewed by 0.31mm for no apparent reason.

Moving on, next part with two mounting hole for a flange (image below), one mounting hole drilled 0.1" lower than the other so the flange needs to be tilted to line up with the holes, when it should be level. How does this happen? I imagined these were built on some form of assembly line with CNC machines drilling holes where they should be, not done by some hungover dude with a Black&Decker drill randomly drilling holes by eye.

I'm following drawings from a fellow that did the same upgrade on the supposedly better PM1022 lathe, some of the exact same defects he discovered are present on both lathes, and he has some defects I don't have and I have some defects he doesn't have. Definitely not made in Germany, Japan or Taiwan type quality.

Okay I'm done.

 

[jorogi]

Sounds like Ford design engineers strike again

 

[Gennady]

not expect to have one of the holes skewed by 0.31mm for no apparent reason

You probably asking for too much

 

[PeterT]

Unfortunately hand drilled holes in some of these machines is just how they do it. One could argue its using lower cost labor but in many instances is just bad engineering & false economics IMO. They could have made a jig or fixture to better control the operation to make it much more consistent & probably quicker than the Mark-1 eyeball. Over time hobby machines from Asia are getting better on average. You can get decent machines but seems like they need to be specified / scrutinized / vetted by a reputable dealer. And those generally cost more. A machine from Germany or Japan, presuming they even make one, would cost you 10x more so choose your poison. Since we don't make anything like this ourselves & the raw material costs more than the finished part, options are somewhat limited.

 

[DPittman]

Unfortunately hand drilled holes in some of these machines is just how they do it. One could argue its using lower cost labor but in many instances is just bad engineering & false economics IMO. They could have made a jig or fixture to better control the operation to make it much more consistent & probably quicker than the Mark-1 eyeball. Over time hobby machines from Asia are getting better on average. You can get decent machines but seems like they need to be specified / scrutinized / vetted by a reputable dealer. And those generally cost more. A machine from Germany or Japan, presuming they even make one, would cost you 10x more so choose your poison. Since we don't make anything like this ourselves & the raw material costs more than the finished part, options are somewhat limited.

It is frustrating isn't it? I think adding a little bit of precision and refinement would not cost much but would make the machine more valuable to most consumers I would think. I've always felt that if the manufacturer on my Asian lathe would have spent another $100 on refinement and precision I would have paid another $500 for the lathe.

 

[David]

When I was doing the CNC conversion on my mill I was shocked at how haphazard the holes were. Even when there was a bracket with holes on a pattern the mating holes in the casting were off.

 

[Tom Kitta]

So I had the same issue with Czech made lathe - this is more or less German level. The holes for mounting the gap in the lathe were very hard to replicate as they were... all over the place. Difference of like 1mm+

Since it does not matter during manufacturing how much "off" the holes are from perfect they are only roughly measured and drilled.

Moral of the story is everyone cuts corners - even top of the line guys. Things may be better in lathes that are made for toolroom precision - so maybe Hardinge level lathes have more spot on parts all over.

 

[ChazzC]

Over time hobby machines from Asia are getting better on average. You can get decent machines but seems like they need to be specified / scrutinized / vetted by a reputable dealer. And those generally cost more.

I have to agree with these observations: when I installed DRO scales on my LMS 3990 Mini-Mill, the factory threaded hole locations were exactly where shown on the LMS DRO kit drawings (I wasn’t using their kit, just happy to use the factory threaded holes). Similarly, I haven’t had any issues in determining existing hole locations on my MicroMark 7x16 Mini-Lathe.

 

[Tom O]

CNC = Civilian not Computer? Perhaps?

 

[Tomc938]

I'm in the middle of replacing the cross feed lead screw with a ballscrew to reduce the backlash. To do so I need to fabricate various mounting blocks to replace the originals. You would think during the design of something like a lathe that if you needed 4 holes in a square pattern to retain say a block you wouldn't randomly choose 9.74mm, when 10mm would easily fit just as well. Further you would not expect to have one of the holes skewed by 0.31mm for no apparent reason.

Moving on, next part with two mounting hole for a flange (image below), one mounting hole drilled 0.1" lower than the other so the flange needs to be tilted to line up with the holes, when it should be level. How does this happen? I imagined these were built on some form of assembly line with CNC machines drilling holes where they should be, not done by some hungover dude with a Black&Decker drill randomly drilling holes by eye.

I'm following drawings from a fellow that did the same upgrade on the supposedly better PM1022 lathe, some of the exact same defects he discovered are present on both lathes, and he has some defects I don't have and I have some defects he doesn't have. Definitely not made in Germany, Japan or Taiwan type quality.

Okay I'm done.
View attachment 63332

German manufacturing: "Is the hole placement +/- .005?" Approved.
Chinese manufacturing: "Is the hole surrounded by metal on all sides? Approved.