View Full Version : PDJ Inc CNC lead screw selection help needed

10-12-2010, 09:26 PM
Hello everyone, I'm building Phil's of PDJ Inc's fantastic design. I've already acquired a wealth of parts for it such as the (rods, linear bearings, aluminum & steel frame metals) I want to get some lead screws selected SOON so I can plan as to what kind of flanges I will need to prep for. The plans call for 1/2, 5TPI which I believe is (turns per inch) for ball screws, which is measure differently?? I want to go the ACME route. I haven't cut any of the steel yet but my 20mm linear shafts are long enough to build a 36x42" design which is bigger than PDJ's plans. I want my CNC to have good resolution and accuracy, NOT something that's only good enough to do cut outs for speaker boxes all day long. I want somethings that accurate enough to etch a name in a dog tag, drill a PCB, do a detailed sign that's 24x30" using vCarve PRO for example. From research, I believe I can get away with 1/2" leads but I don't have any idea on the threads per inch.. 8, 10, etc.. and what number of starts which yield me great accuracy.

The motors of choice are the Keling Package (Gecko G540 w/ 381oz steppers) This will be a dual lead screw for the Y axis setup.

I hope I provided enough information. If you need any further info that would help, please let me know.

Thanks for any info.

10-12-2010, 11:29 PM
sent an email last night to Tim over at dumpstercnc.com I just got a response back from him. He recommends 1/2-10 5 start for all axis'. He states it will give plenty of good accuracy for the above. I trust his word. Anyone 2nd this?


10-13-2010, 10:44 AM
Yes his stuff is good and I would go with 1/2-10 5 start. It is what I used on my router. It is plenty accurate and I could not imagine going with anything slower. It seems to have a very good balance of speed and precision.

10-13-2010, 10:26 PM
Thanks very much for your response to my post. I feel good after you seconding this. I will place an order with dumpstercnc in the morning.

Thanks again.

10-14-2010, 10:32 AM
Like I said I am running these screws on my table and only one screw per axis. MLy long axis is 52" and I do not have any screw whip at all.