Pictures of the PM-833T

rwm said:
I believe this would make and awesome CNC machine! Blue-luke- what specific DRO did you order?
Click to expand...
An Ebay store in China. There are many and here is a few pointers:
- If you can spring for a bit more $$, the 'Sino' brand is very good but quite a bit more expensive. About 1 1/2 times more
- Watch more than just the price! Some at first looks more expensive but includes standard shipping, one was only 245$ but charged 145$ for standard shipping!, even more for DHL/FEDEX/UPS
- Albeit taking quite long, I never had problems with standard shipping from China, but do get a tracking number.
- For a 3 axis you will pay about 300$ US +/- 40$
- Some are sold with certain scales lenght only, of course you want to get the proper scales for your machine!
- when specifying the scale lenght, remember that usually it is the travel length that is specified, the module itself is about 6 inches (150mm) longer than the travel
- most of the mounting kits and brackets supplied are so-so and you will end up probably making your own as every machine is different and need adaptations...
- Throw the supplied screws and nuts in the garbage!
- The one I just ordered looks exactly the same as the one (2 axis) I have on my PM-25 which I bought used and installed in 2012. No problems whatsoever so I figured that buying the same type would at least save me the pain of learning and using different user's interface as I know all the basic functions already.
- These have many many functions, including a calculator mode! I prefer to do all my calculations either in my head or on a pocket calculator for one, and really, on a mill the only functions I found really handy are : bolt circle pattern, sets of hole position, absolute and relative measurements.
That's it!
- I find very convenient to switch from imperial to metric at a press of a button!
- All those user's interface use nice big bright digital displays, but the layout of the whole thing is a bit fuzzy and cluttered. Not to a point where it becomes akward but there is a certain adaptation to make in your brain.

I don't know if it's proper to post this here, but here is the link to the one I bought. I have no affiliation whatsoever with the vendor, in fact it's even the first time I deal with him. So when you buy, from him or another one, before commiting the plastic money, get in touch with them and specify what size of sclaes you need. Up to 1,000mm (1 meter or about 40 inches) the price is the same for any combination of sclae lenghts.
So I wrote to him, specifying my needs, and he replied (verbatim) "OK, just pay" !!! I strive to be polite, but this was awfully straight to the point! :)

I am not insulted by this, His English, albeit sketchy and heavily googled up, is surely better than my Chinese!! ha ha :)
 
Blue Luke.... Your link to the DRO you bought did not work, or you forgot.

The more I think about this, the more I am inclined to just order a DRO for this machine to get me going. One of our members, Bob Korves, recommended one that he got from AliExpress.
Here is a link to it.
DRO system. Siton Technology Store Seems like a great deal, although I will upgrade the scales to 1um instead of 5um, I think. Would it be worth it (+$18 extra per scale) to upgrade the scales?
 
A DRO will make your milling experience SO much more enjoyable. And speaking from personal noob experience, more accurate & fewer errors.
I wish the low cost DRO systems available today were around 15 years ago.

Not sure what it has for Z axis but if its anything like my RF-45, you can make up brackets to suit & integrate an encoder into a 3-axis DRO display box. Or go for the digital vernier style.

Does that mill have a power down feed?

J2048x3072-08040_edited-1.jpg
 
petertha said:
Does that mill have a power down feed?
Click to expand...

No, it does not have a power down feed.
You bring up an excellent point though for me. Where is the typical Z axis mount done? Is it attached to the quill or the vertical column? I am assuming that based on Blue Luke's earlier comment in this thread about lengths of scales that it would be installed on the column.
 
DRO doesn't do you much good on the column of these type mills. That's kind of a rough positioning. You want it on the quill, that's the fine feed for actual milling or drilling depth control. Your layout is somewhat similar to mine, that's why I showed my arrangement as example. Your choice scales will dictate where brackets & mounts can & cannot go. I didn't want to drill holes into the oil bath head so this is what I came up with. I'd give Matt a call for ideas. maybe he has done one already, or surely he must be contemplating others outfitting theirs.
 
7milesup said:
Blue Luke.... Your link to the DRO you bought did not work, or you forgot.

The more I think about this, the more I am inclined to just order a DRO for this machine to get me going. One of our members, Bob Korves, recommended one that he got from AliExpress.
Here is a link to it.
DRO system. Siton Technology Store Seems like a great deal, although I will upgrade the scales to 1um instead of 5um, I think. Would it be worth it (+$18 extra per scale) to upgrade the scales?
Click to expand...

Check with Matt at QMT, he probably can give feedback on the scale resolution that would be best for the 833T.

I think 5um would be OK, that's what I have for my mill, IIRC Matt recommended the 1um for the lathe cross slide only.

Nice job on the stand.

David.
 
Last edited:
Higher resolution scales are never really a bad thing, but on the garden variety mills that we hobbyists have, we are not going to see real gains in overall accuracy with the work we turn out because we have .001 mm scales. Our machines, while they are pretty amazing, are just not that accurate and repeatable. The real issue is that seeing the higher resolution digital numbers makes us think we can get closer, and spend extra time and effort chasing rainbows.

Cross slides of good lathes and the down feed on surface grinders, if they are actually doing high tolerance work, is where high resolution scales are really useful -- IMO.
 
Just got off of the phone with Matt (love his customer service!). He installs the DRO's on the head of the machine for the Z axis. If I want one on the quill, he suggested something simple like an igauging type of system. He also said 5um would be fine, just as Bob ^^ did. So, just need to figure out exactly how long of scales I need and get it ordered.
 
On my PM25 and 9x40 bench mills, I had the Z-axis scale on the head. Works very well if you know how to use it. :)

Added a digital scale on the quill for drilling which was the only time the quill was extended beyond a 1/4" or so.
 
Last edited:
7milesup said:
Just got off of the phone with Matt (love his customer service!). He installs the DRO's on the head of the machine for the Z axis. If I want one on the quill, he suggested something simple like an igauging type of system. He also said 5um would be fine, just as Bob ^^ did. So, just need to figure out exactly how long of scales I need and get it ordered.
Click to expand...
It is possible to install both head and knee scales and have them be additive, where you can move the knee up for part of the feed and run the quill down for the other part, with the readout summing both motions. There is a black box available to do that, and some systems might have that capability built in. Here is an example:
https://www.sra-measurement.com/m-dro-linear-encoder-summing-interface.html
Edit: for that unit both scales need to be quadrature...
 
You must log in or register to reply here.
Back
Top