[craftech]

Hello my question is what type of leed srew should i use for my machine
I have 253 once steppers and dont want to compromise strenght.
I think if i use threaded rod it wont be as fast but stronger and if i use acme screws wide thread i guess the steppers will work more harder and also faster
Can someone help me with this question
Thanks

[High Seas]

How long are the axes? How will you support the threaded rod? Have you considered rack and pinion - saw my first one -- up close and personal -- and I might try that next for a big machine. Size is a big part of the equation as well as torque, rpm, etc.
Jim

[ynneb]

I have used allthread on my Z axis.( Much to many purists disgust)
If you use a metric thread you will get a nice fine pitch. I guess if you have a small table then a fine alltherad is good. I wouldnt want to use it on a large table though because it would take all day to travel. Not to mention the speed wobble.

What sized table are you building?

[craftech]

the style of machine is gantry the fixed table is aprox 24x36 inches i want to carve out wood 3D an mill some t6 alluminum parts out of sheet alluminum this will ride on thomson linear bearing and thinkin of using a small 1/4 router with ajustable RPM'S
Precision is my goal here not speed

[ger21]

Precision is my goal here not speed

You'll probably change your mind on that while you watch it s l o w l y move back and forth.

The more threads per inch, the more power (and finer resolution) you'll have. A good middle ground is probably 1/2-10 Acme. Get precision acme, not the really cheap stuff. Acme is really a much better choice, because it's much smoother threads will transmit power much more efficiently.

[craftech]

thanks gerry i am sold this is what i will use and be looking for OK I also took a stepp down from your advisse for the stonger steppers but once built and running i will probably agrade in the long run to bigger ones and drivers to i guess right now just collecting all of the parts needed for the project i was looking for a alluminum table very thick so i can machine T slots in them but the price of that piece is $$$$$$ so i found a nice piece of 1 inch thick ( hight density polyethelyne ) that think will do the trick and for 1/4 the price of the alluminum and easy to machine, hope to post some picture somday soon ,not sure how to do this on this site but i am sure someone will tell me EH
Brian

[buscht]

Brian, I am using 5/8" dia ball screws available from www.mcmaster.com. The rod is about $1.10 per foot and the nut is about $20-$25. Accuracy is .004" per foot.
Its 90%+ efficient so you will good power transfer. They work very well, but its hard to grind and turn the ends down for bearings, plus you need a special tap 15/16-16 for the nut mount, or you need to buy a mounting plate for another $20

You stated that you wanted accuracy, not speed. You might want to reconsider the 1" polyethelyne for the table top. I think it grows and shrinks quite a bit depending upon temperature and humidity. MDF with aluminum Tee slots might be a cheaper/better way to go and be just as accurate.

Maybe someone with more knowledge about plastics can make a definitive statement.

[BigDaddyG]

Brian,
MSC sells a Precision Acme that is quite reasonable in price! It is Nook and has a +/-.003 (Anti Wedging 2-C Thread). I have used these many times and very happy. They are easy to turn the ends down, or you can buy all the end blocks etc. Plus they sell the lubricant as well if you need it. I use the Bronze nuts for the most part and again been very happy with the results.
Regards,
Glen

[ger21]

I got my 1/2-8 2 start from MSC, ~ $23 for 6ft. It's cheap enough so that if you find you need more speed, you can swap the 1/2-10 for the 1/2-8 2 start and go twice as fast (if your steppers have enough power ). Or even 1/2-10 5 start

Note: Mine is Kestone, not the Nook. A little less accurate,(.009/ft) and less than 1/2 the price.

[craftech]

Hey guys great advise and last nite i think i got screwed i bought a 3 foot new acme 1/2-10 lead screw on Ebay for 24.00 $ !!!!!!! i will use this for two axis only and going to look for the Z axis complet with anti backlash nut and have to find twoo more for the others not to shure how much i should pay for those I not shure how long of screw for the Z I want a least 5 to 6 inches of travel so how long should the table for that axis be ,i was it would travel down a maximum of 1/2 its lenght for strenght purposes so i guess a 12'' lead !!!!!!!!!!!!!!!!!$%^%&^^%^$!#4

Brian