I am laying out a floor plan for a small garage shop. Has anybody built a mill enclosure for the PM-833TV. I do not have the mill yet so estimating the enclosure size is a bit tricky. From the PM specs, I have estimated the width and depth to be 72" x 36". I am not concerned with the height as my ceilings are 10 feet tall. I would greatly appreciate it if someone who has the mill or built and enclosure can help me with these dimensions.
Mine is 69” wide x 45” deep. My steppers are huge so it added some to both dimensions. Make sure you leave space (or a way to open the enclosure) on each end to be able to slide the bed off of the mill.
Thanks so much for you reply. This is very helpful. I have decided to move ahead with the PM-833TV and will order it as soon as my new garage is completed.
I am still perplexed with the choice of steppers/ball screws required for the PM-833TV. The PM-833 is lighter than the PM-940. That guys at Arizona CNC who have built more conversion kits than anyone use a 1700 ounce stepper for the Z-Axis for the PM-940 and claim it has tons of torque for the job. They use either a 25mm or 32mm balls screw for the Z-axis. By contrast the ball screws from Bruce Nelson at Heavy Metals for the PM-833TV are 20mm and they suggest using a 2800 oz. stepper for the Z-axis. I don’t understand the use of a significantly larger stepper and a lighter duty ball screw.
Dr. D said he chose the 2800 oz stepper for added detent torque needed to hold the head stationary when the mill is depowered. However if the 1700 oz. stepper has enough detent torque to hold the PM-940, then I would think it would have no problem with the PM-833. Any thoughts on this?
I also just read a post on this forum from Sean about adding a gas strut to off-load the Z-axis. He noted
“The main reason I wanted to add the gas struts was to take the load off the double ball nut. The Z axis was not sounding smooth while in motion as compared to the X and Y. I was concerned running with that load on the double ball nut was going to lead to premature wear or failure of that mechanism.”
Todd, did you have to add a gas strut to the Z-axis? Did you use a 20mm ball net for the Z-Axis?
Thanks again… Richard
I used a set of easy servos. Nema 34 for x and y and nema 42 for Z. The z is a 2832 oz in. There aren’t many choices in this style but there was a 1700 as I recall. I’m sure that if Arizona CNC says that the 1700 works it is probably correct. Wish they made a kit for this mill. I wasn’t sure so I went bigger. It is huge.
I haven’t had any issues with the Heavy Metal kit other than I had to make my own mounting plates for some of it. Mostly because The mill has some random threaded hole positions and I wanted lower gearing on Z. I did not use any gas struts but not a bad idea if it is properly set up. Probably would help with my much heavier spindle motor.
Thanks Todd. I have a 1700 oz. stepper and driver so I am going to give it a try. Stepper online offers the same 1700 oz. with an optional brake, so if it does not work I will swap it. Bruce Nelson recently modified the Z mount to accept both Nema 34 or Nema 42 motors.
I also found a metric motor from Techtop motors in GA so if I ever choose to upgrade the motor it should be close to plug and play. Thanks again for all your thoughts… Richard
No problem. Nice that the brake is available if needed. I really have no idea if the larger motor is really needed.
After reading all the comments on this forum, I pulled the trigger and ordered the PM-833TV and small lathe. Just a quick question on the mill enclosure. I was planning on making a short bench to support the mill, then building the enclosure from aluminum extrusions and plexiglass. I was thinking of mounting the fog buster and a mounting bracket for my touch screen monitor on the right side of the enclosure. This would allow me to store the monitor on the side of the mill, then swivel it to the front when using the mill.
I just remembered that you suggested having the ability to open either side of the enclosure to slide the bed off the mill. Once the mill is setup, when would I need to slide the bed off the mill?
Todd, sorry to resurrect this thread, but I noticed you mentioned lower gearing on the Z-axis. I have the heavy metal kit, but Bruce left out the timing belt and timing pulleys and then tragically passed away right before Christmas. Do you happen to have the specs for the belt and pulleys you used? I’ve never worked with timing belts+pulleys before and am a bit out of my depth.
I never did see this question from you. Sorry for the very late response.
The only reason the remove the mill table is if you need to replace or maintain the X or Y ballscrew components.
I will dig them out of the archives but just so you know, I modified the z-mount to accommodate the pulleys I used. At the very least I can get you some specs and you can find the diameters that will fit. I’ll get back to you shortly.
I looked up the pulleys I used and here are the McMaster Carr #’s:
Ball Screw Pulley: 1304N14
Motor Pulley: 6495K15
I cant remember exactly why I had to make my own motor base plate but my recollection was that the hybrid stepper I bought had different dimensions including the shaft. The combination of many factors, including the hub of the new pulley interfered, forced me to make my own. I attached a lousy pic of this.
Another option is that I may have the original pulleys and belt from my kit. I will have to dig through my boxes of parts but they are probably there. They may not be the correct shaft size for you however. Let me know if you would like me to dig these out. If so, give me the shaft size on you stepper and the ballscrew so I can confirm.
You are correct that Bruce Nelson passed away suddenly, however the company is still functioning. I received the PM833 Kit a few days ago. Have you attempted to call or email them?
I too don’t know much about these items but here is what I have:
The belt is marked: SDP A 6R 4-033050 M125
Large Pulley: 53.9 mm dia x 31.86mm tall
Small Pulley: 41.89 mm dia x 30.34 mm tall
Let me know if I can help in any way… Richard
Thanks… That is what I thought.
No rush at all. That will be a lot of help either way. Thank you.
Thanks loads. I was actually able to get a portion of that belt number off of the instructions PDF but couldn’t find anything via Google. That’s awesome. I should be able to derive what I need from that info if I have to source it myself.
I have emailed email@example.com but haven’t heard anything yet. It’s only been a single day so I’m not surprised at that. I’m glad to hear that they’re still shipping. Best of luck with your project.
Sorry I was running out the door earlier. I meant to add that the large pulley has 18 teeth, and the small pulley has 14 teeth. I hope this helps… Richard
Just for fun I jumped on to McMaster Carr. I am fairly certain these I have located your pulleys:
Large Pulley (English): McMaster-Carr
Large Pulley (Metric) McMaster-Carr (The hub diameter is a closer match than the English option, but it probably would not matter.
Small Pulley: McMaster-Carr does not appear to have a 14T pulley with a 14mm or 1/2" shaft diameter. Using the specifications on the McMaster website. Here are the specs for the smaller pulley:
OD: 1.90 inch
Belt width: .50 Inch or 13.6 mm
Inside Wd. .559 Inch
Outside Wd. .736 Inch
Overall Wd. 1.19 Inch
Hub Diameter: 1.25 Inches
Please let me know if I can help… Best of luck…Richard
Thanks again man. I’ve ordered the ones from the link in my previous reply
Todd, thank you again very much, RJS recently got his kit and gave me the dimensions off of his and the part number from the belt and I was able to source them.
Thank you both very much.