ACME / Trapezoidal leadscrews

Yet another question in my bid to gain knowledge :).

Does anyone know the metric trapezoidal equivalent to various ACME leadscrews?

ACME leadscrews are sized as say 10tpi single start, so 10 rotations = 1 inch of travel. A 10tpi 2-start has 5 rotations = 1 inch of travel, in metric land the 10 tpi single start is equivalent to a 2.54mm pitch trapezoidal leadscrew I believe, but what is the equivalent to the 10tpi 2-start? 5.08mm 2-start?

This is almost frustrating, I started out thinking 'I want to do ZXY', but every time I look at any particular part it throws up more and more questions :eek:. Fortunately I love meeting challenges, and solving problems so this is still fascinating & fun :D.

Just to give some idea of what I'm thinking, my plan is something like this:
I want to build a basic router as a learning exercise, that I can then use to make the (first :D) proper router with. I am thinking of the proper router being something similar to the Joe's 2006 R-2, and to save money I want to build the basic one using parts that can be reused, i.e. x-axis leadscrews and bearings of the basic becoming the y-axis of the Joe's 2006.

If you think I'm completely mad let me know :D I already know I'm slightly mad ;).

Or if you've got any suggestions for different machines, parts, or anything really, please speak up :).

BTW the reason for the original question in this post was that alot of people in the states are using 10tpi 2-start, or 8tpi 2-start ACME rods with success in their Joe's 2006 routers, and I don't want to blow £30+VAT and delivery on the wrong material...

basic rule of thumb is Acme is usually imperial, trapezoid is usually metric so you get 1/2" acme versus 12mm trapezoid, also often know as power screw over here.

Acme is usually a cut thread and trapezoid is usually a rolled thread.

Another thing to bear in mind is that 10 tpi two start is worked out as 5 tpi, the greater the tpi the more torque you need to move a carriage.

Good website here.

http://www.kingston-engineering.co.uk/exstock.htm

John S.

Thanks John, had a look at that web site, and it didn't clear the fog from my brain :confused:, but then I found http://www.automationcomponents.co.uk/ things are making sense now :).

As I understand it (using Marchant Dice codes as an example) a TR16-8P4 screw is 16mm in diameter, would move 8mm per revolution, and has 4 starts. Anyone able to confirm this for me?

Also MD don't seem to sell multistart nuts at all?! seems a bit strange.

Quote:

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Originally Posted by John S

Another thing to bear in mind is that 10 tpi two start is worked out as 5 tpi, the greater the tpi the more torque you need to move a carriage.

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Don't you mean the lower the tpi the more torque? I don't need help with being confused ;). Ignoring efficency issues 5 turns per inch of travel has to take more torque than 10 turns per inch.

Just testing to see if you are awake...............:D

John S.

did u happen to find any acme 5/8 5(2) nuts [ie 5/8 diameter, 10TPI and 2 starts]
so far i only see stuff at roton , around $25 or more per nut...

Sorry, not been around for a bit.

I've had to stop plans for my router for a while due to job issues :( so I've not been looking, I had pretty much decided to go with delrin drive nuts, and make them myself by using a section of leadscrew to make a tap for the threads.

[QUOTE]I think I have a Bad Delrin Trapezoidal Metric SCREW NUT? I think it's16mm? It's for a 3040t CNC. The X-Axis won't move along the Leadscrew with the Motor Spindle. The Nema 23 Motor doesn't move the Spindle from Left to right or vice versa, The Nema Motor turns without anything on it. It works on it's own with no Spindle Motor movement?. It seems like the Nut is Bad, and the Leadscrew isn't turning thru the threaded Oval shaped Delrin Nut? It's Stripped. Where can you get a new Delrin Trapezoidal Metric Nut? I cant wait 40 days from China. They say a lot of Businesses are closed due to the Corona Virus! This Machine is Brand new never used. I'm trying to learn Mach3 to run it.!
Thanks,
Tom Megna

Ahar!, you can't escape by jumping to an even older thread.

If you've resolved that your problem is the nut, and that it's a Delrin nut, then your task is simple - identify the thread type and pitch and look for a US supplier. Or, consider the replacement of the screw together with a nut it that's easier (unlikely!).

Before that, though, get eyes on the nut and make sure that there is no adjustable component.

Once again, answering this blindly is impossible to give good clear advice. Create your own thread, post pictures.