Where do you get your ACME screws?

[kolias]

Thank you Satanklawz, I just found the Dumpster couplings and I think they are great. Thinking to go the same way.

Trell ENCO does not carry 5 start acme and I think they are more expensive. Thanks anyway

[CarveOne]

Thank you Satanklawz, I just found the Dumpster couplings and I think they are great. Thinking to go the same way.

Trell ENCO does not carry 5 start acme and I think they are more expensive. Thanks anyway

I started with the low cost Enco 1 start rods and changed to McMaster-Carr 5 start rods later. Yes, at ~5x the price the 5 start is 10x better for your machines in a number of respects. Mainly it's faster speeds and less (or no) problems with step motor resonance.

CarveOne

[Rotax91]

Hello Ger,

I posted early in this thread. I'm still in the build process. I've been thinking alot about what ACME material I want to purchase. Either 1018 or 4140. This machine will be in my garage. Here in WI, our summers can be very humid. I don't want to run into corrosion and rust issues so I'm leaning towards the 4140 black oxide ACME rods. What I'm afraid of is turning the ends to fit my 1/4" ID bearings. My question is: How hard is this stuff to cut being that it's hardened. In your post #13 above, it looks like your rods have the black oxide finish and you are turning them with a stone so I'm assume it's not that bad to cut -or- aren't yours heat treated? I have access to a lathe but I'm by no means a professional. What am I in for if I choose the 4140 and turning the ends down?

I had to tap holes in my 20mm hardened linear rods for standoffs. It was a bear!!! I hope the 4140 is easier.

Thanks.

[CarveOne]

Hello Ger,

I posted early in this thread. I'm still in the build process. I've been thinking alot about what ACME material I want to purchase. Either 1018 or 4140. This machine will be in my garage. Here in WI, our summers can be very humid. I don't want to run into corrosion and rust issues so I'm leaning towards the 4140 black oxide ACME rods. What I'm afraid of is turning the ends to fit my 1/4" ID bearings. My question is: How hard is this stuff to cut being that it's hardened. In your post #13 above, it looks like your rods have the black oxide finish and you are turning them with a stone so I'm assume it's not that bad to cut -or- aren't yours heat treated? I have access to a lathe but I'm by no means a professional. What am I in for if I choose the 4140 and turning the ends down?

I had to tap holes in my 20mm hardened linear rods for standoffs. It was a bear!!! I hope the 4140 is easier.

Thanks.

Either type metal should be easy enough to turn with a sharp HSS or triangular carbide insert cutter. 1018 is cold rolled steel. 4140 is gun barrel steel. They aren't that hard to cut on a lathe. Stoning is usually done to finish the last few thousandths to be smooth and to bring it down to exact size.

CarveOne

[louieatienza]

I started with the low cost Enco 1 start rods and changed to McMaster-Carr 5 start rods later. Yes, at ~5x the price the 5 start is 10x better for your machines in a number of respects. Mainly it's faster speeds and less (or no) problems with step motor resonance.

CarveOne

Yes and also more usable power from the steppers. Another thing is less premature wear since the screws aren't rotating as much or as fast.

As for turning down the ends... dumpsterCNC sells ACME threaded couplings. It might be easier to get a 1/2" ACME - 1/4" round coupling, and then attach 1/4" drill rod to the other side of the coupling, which should fit nicely in your bearings. They don't cost that much, and considering the time you need to turn the screw ends, might be more cost-effective time-wise.

[CarveOne]

Yes and also more usable power from the steppers. Another thing is less premature wear since the screws aren't rotating as much or as fast.

As for turning down the ends... dumpsterCNC sells ACME threaded couplings. It might be easier to get a 1/2" ACME - 1/4" round coupling, and then attach 1/4" drill rod to the other side of the coupling, which should fit nicely in your bearings. They don't cost that much, and considering the time you need to turn the screw ends, might be more cost-effective time-wise.

Those are what I normally use. More recently I made some shaft ends that fit over the ACME rods that had a step-down to 1/4", pinned them to the ACME rods with a roll pin, and used DumpsterCNC 1/4" to 1/4" couplers I had on hand. I was reusing ACME rods from a previous build and needed a little more length than I had available.

CarveOne

[jjacstcy]

So 4140 is preferred over 1018? Anyone got a part number for 4140 1/2-10 5 start from Mcmaster?

[jjacstcy]

Answered my own question, the 4140 is the black oxide rods. Me no want them...I remember seeing a thread that said they are worse on plastic nuts as far as wear.

[Drools]

I'm not sure about that, I ordered the Black Oxide rods from McMaster. The screw seemed to have some sort of gunk on it. Not sure the purpose but after cleaning the screw in some mineral spirits it is smooth as silk. Without cleaning the screw it seemed rough the gunk reminds me of the stuff used on a tack cloth. I would not have considered running them without a good cleaning. I will do as Gerry does and use some light oil for lubrication.

[CarveOne]

I'm not sure about that, I ordered the Black Oxide rods from McMaster. The screw seemed to have some sort of gunk on it. Not sure the purpose but after cleaning the screw in some mineral spirits it is smooth as silk. Without cleaning the screw it seemed rough the gunk reminds me of the stuff used on a tack cloth. I would not have considered running them without a good cleaning. I will do as Gerry does and use some light oil for lubrication.

That gunk was a rust preventative coating. If the black oxide treatment is the same as the black oxide coating on button head screws it will easily rust when moisture in the air condenses on it during warm-up after overnight sub-freezing weather. It will probably wear off to some extent during use. I haven't looked at these rods in person, so someone who has them may be able to confirm how durable the oxide coating is. In any case, some sort of lubrication should be used to help from wearing Delrin anti-backlash nuts.

CarveOne

[jpike10]

i just received part # 98940A204 from Mcmaster carr 1/2-10 5 start its 4140 heat treated and they where not black oxide coated although they advertise them being such . I am in the middle of my build and have not installed them though.

[ahren]

Another option rather than turning down the ends is to pass the screw directly through a 1/2" bearing, or to couple to a piece of drill rod that passes through the bearing. By sandwiching thrust bearings on either side with shaft collars, you effectively account for thrust and radial loads. To make things even easier, you can use one of our shaft adapters to do this -- it's basically a 1/2" rod coupled to a 1/2" clamp collar to go around the screw:

CNCRouterParts

Ahren
CNCRouterParts

[kolias]

I bought mine from Nook Industries, $30.00 less expensive each 6 feet long rod, than MacMaster. According to MacMaster, the 4140 Alloy Steel ensures greater strength and durability.

To my opinion there is no benefit of 4140 vs 1018 for the average CNC user. If you use them in an industrial environment and under constant heavy load perhaps 4140 will be better. I have used 1018 in both my hobby CNC’s and never noticed any problems.

Regarding the black oxide, that is not a coating but rather a finish of the material as per MacMaster description. Mine arrived with a shiny black finish (black oxide?) and a thin film of oil. I just wiped off the excess oil and slipped on my Delrin nuts. No extra lubrication is required for the Delrin nuts.

I have operated mine in my garage which is semi heated in the winter and never noticed any kind of corrosion.

[jjacstcy]

The are threads on here about the black oxide rods stating that the finish is more porous the the 1018. They also state that since they are slightly more porous that they generate more heat resulting in the melting of the delrin nuts. Just what I have read, don't know if it is true or not.

[ger21]

Hello Ger,

I posted early in this thread. I'm still in the build process. I've been thinking alot about what ACME material I want to purchase. Either 1018 or 4140. This machine will be in my garage. Here in WI, our summers can be very humid. I don't want to run into corrosion and rust issues so I'm leaning towards the 4140 black oxide ACME rods.

It's humid here in MI too. However, I keep my screws lightly oiled, so rust wouldn't be an issue with either type.

What I'm afraid of is turning the ends to fit my 1/4" ID bearings. My question is: How hard is this stuff to cut being that it's hardened. In your post #13 above, it looks like your rods have the black oxide finish and you are turning them with a stone so I'm assume it's not that bad to cut -or- aren't yours heat treated? I have access to a lathe but I'm by no means a professional.

I used an angle grinder, which was quick. Never used a metal lathe, so can't help you there.

[Rotax91]

Hello guys, thanks for the overwhelming responses today. It helps me quite a bit. Ger- I really feel assured now that you are running 1018 and not experiencing any rust issues. I've been to MI and I know it can be very humid there too. I'm leaning towards the 1018. Something I found last night was some rods coming with a PFTE teflon coating on them. I think it was Nook that carried them. So I was thinking of getting the spray in this link below. Only problem is that my oven isn't big enough for my 42" Y rods to be able to heat treat the finish. Maybe I'm over thinking this too much.

Teflon coating.
BROWNELLS : TEFLON/MOLY OVEN CURE, GUN FINISH - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools - BROWNELLS

Here is a link to show how teflon coated screws look.
HB2 Construction

[ger21]

I don't have the 1018, I have black oxide.

I was just saying that I keep them oiled.
If you keep the 1018 oiled, it won't rust.