Has anyone used ACME Threaded Rod from Fastenal?

[HayTay]

ACME threaded rod from Fastenal appears to be attractive from a price standpoint. For example, 3/8"-12 x 6' ACME Low Carbon Steel Threaded Rod is listed at $16.52 on their website (Fastenal Part No.: 47547 ). That's right, 6 feet for less than 20 dollars. Even better is that there is a Fastenal Retail Store about 3 miles from where I work so I'll save shipping costs (and damage).

Has anyone used ACME Threaded Rod purchased from a local Fastenal store for their builds? Pros? Cons? Should I save my money and purchase a higher precision ACME threaded rod from McMaster-Carr (part #98940A594) or somewhere else?

For reference, I'm planning on using the 3/8"-12 ACME threaded rod coupled with the 3/8"-12 AB leadnuts from dumpsterCNC.

On the other hand, Fastenal's 3/8"-12 Plain Finish ACME Nuts are listed at $2.86 a piece!!! That price seems to be more than a bit steep to me. Anyone have any sources for less expensive ACME Nuts?

HayTay

[ger21]

MSC has precision alloy 3/8-12 for less than Fastenal. http://www1.mscdirect.com/CGI/NNSRIT...PMT4NO=4301428

[KaptainKarst]

Got mine here
http://dependableacme.com/
Purchased (2) 6' x .75" x 10 tpi.
came well packed and not bent.

[jeffs555]

The Fastenal price seems a little high for general purpose low carbon rod, but it does have the advantage of being locally available. www.use-enco.com has Keystone low carbon C1018 rod in 1/2-10 at $7.99 for 6 feet. Both are probably 2G general purpose rod.

As for whether you need precision acme rod, I have been trying to find an answer myself. I have been trying to find some discussion of the differences between 2G general purpose, and 2C precision acme rod. The best I can tell, the main difference is the clearance between the rod and the nut. Supposedly this mainly effects the backlash. Since I am tapping my own delrin nuts with a tap made from the same rod, I am not sure how this affects things. I don't know if the price difference is worth it. If someone has more info on the subject, I would sure appreciate it. The only info I could find on the web was on these two pages.

http://www.liutaiomottola.com/Tools/Backlash.htm
http://www.landisthreadingsystems.co...hreadforms.pdf

[dertsap]

i used acme rod from fastenal , i ve hooked up 3/4"-6 to my small nema 23 vextas , runs great and runs twice as fast as the 1/2-13 rod i had previously , i d be a little worried about the sagging and rigidity of 3/8 rod over any span , i have pillow blocks on each end , this thing spins freely , keep in mind the less tpi the faster your moving , and as far as the price goes whats the point of worrying about a couple of bucks , you can have a cheap machine for cheap or have a good machine for a coupla bucks more
if your going to go for such a high tpi i would suggest use ready rod , it s dirt cheap

the only thing i didn t like about fastenal rod was the burrs and the chips , blows me away that a company machining parts can t even blow off the chips , LAZY, but after some cleaning , i m happy

[HayTay]

The ability of the 100 oz/in, NEMA 23, 6mm shaft stepper motors I'm using to drive a larger diameter ACME threaded rod was a concern of mine. I'm amazed to find that Derstap is driving a 3/4" rod with a similarly sized motor. And he's doing that on all three axis? What is the length of the longest axis? Any issues at start of motion or reversing direction with the larger diameter shaft?

I'll check out those sources mentioned so far and start to think about moving up to 1/2"-10 if there will be no problems putting it in motion.

HayTay

[ger21]

As for whether you need precision acme rod, I have been trying to find an answer myself. I have been trying to find some discussion of the differences between 2G general purpose, and 2C precision acme rod. The best I can tell, the main difference is the clearance between the rod and the nut. Supposedly this mainly effects the backlash. Since I am tapping my own delrin nuts with a tap made from the same rod, I am not sure how this affects things. I don't know if the price difference is worth it. If someone has more info on the subject, I would sure appreciate it. The only info I could find on the web was on these two pages.

I bought the alloy Keystone from MSC (1/2-8 2 start). It's extremely smooth. I'm assuming the standard cheap acme has a much rougher finish.

[jeffs555]

Gerry,
I got some of the cheap Keystone rod from Enco, and it is also very smooth and not rough at all. I don't have my machine finished yet, but have tapped some delrin nuts, and they run very smooth turning them by hand. The Keystone web site says that all their rod uses the same rolled thread process. The best I can tell the main difference between the general purpose C1018 Keystone from Enco, and the precision 4140 alloy Keystone from MSC is the difference in tolerance between 2G and 2C. The 4140 alloy does have more tensile strength and better wear properties than the C1018 but I am not sure how much difference this would make in a home machine with plastic nuts.

Jeff

[jeffs555]

The ability of the 100 oz/in, NEMA 23, 6mm shaft stepper motors I'm using to drive a larger diameter ACME threaded rod was a concern of mine.

http://www.compumotor.com/catalog/catalogA/A60-A62.pdf

I found this document that shows at the bottom, all the equations to calculate the torque required to accelerate a load with a leadscrew. I haven't worked through all the calculations, but the example they show uses a 36" long, 1.5" diameter leadscrew with plastic nut, to accelerate a 200 lb load to 120 ipm in 0.1 seconds. Their calculations say this needs 172 oz-in of torque. The majority of the required torque is due to the rotational inertia of the screw. The equations also show that the rotational inertia is proportional to the 4th power of the radius, so a 1/2 inch screw should have 80 times less inertia than the 1.5" screw they use in the example and would need much less than the 172 oz-in in the example.


Jeff

[dertsap]

my table is a heavy 48" x 24" ,i need to lean it out some , like i said pillow blocks on each end and it rolls freely, my motor are rated at 118 in-oz unipolar , my concern was the size of the rod at the time , but for what it is worth if it didn t work then i d sell the motors on ebay ,buy new motors on ebay , and i will still do that later , i m building now but planning for later , even if i had to gear down to a 2:1 ratio ,the feed rate would be the same as the high tpi threads ,and id still have the rigidity , a guy can build a machine that can move fast but it isnt much good if the lead screw is bowing , the torque and accuracy on the tool itself will be lost
for now it works for me
and as far as a lot of a lot of theories and formulas , there is almost always a mechanical way to make something work , for example : calculate the leverage to move an 800 lb tombstone on a horizontal mill table , now when i put way lube oil on the table to prevent corrosion between the tombstone and the table , i have to keep my hands on the tombstone until it is bolted down or it will slide right off the table , trust me it almost happened

[HayTay]

I took the plunge (pun semi-intended) and purchased two 1/2"-10 x 6' Keystone ACME threaded rods from ENCO. The threaded rod is currently on sale for $6.99 each. What a bargain! Tossed in a handfull of 1/2"-10 ACME nuts ($0.99 each) and some miscellaneous end mills to make the total to just over $50.00 so I could use the FREE SHIPPING DISCOUNT CODE posted in another thread.

ENCO Free Shipping Code for FEB 2006: WEBNRFB6

Thanks to everyone for their advice,

HayTay

[spalm]

Go Harry!
Keep us posted when using them.
Steve