Re: leadscrew
Posted by
turbulatordude
on 2005-07-02 09:08:45 UTC
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Chris Horne" <chris@s...> wrote:
you can heat the stuff up and have a mess. Not sure how fast that
would have to be though.
Delrin is the plastic most people talk about.
The shafting you listed appears to be ballscrew stock in term, but
also is listed as trapezoidal so it might be ACME. not sure.
One thing you can do is to grind an end to is acts like a tap.
My experioance with threaded rod is that the surface is rough and will
tear up the plastic. I put my screw into the lathe and spun a die
over the length to remove any dings.
then with my thumbnail and some paper towel, I ran it so my thumbnail
would thread itself along the length. every time I hit a rough spot,
I used a small file and removed the roughness.
I repeated this until I could go from end to end with no roughness.
As for plastic nuts, the goal is to have about 20 threads engaged.
Only a few threads will allow the differences in peaks to effect the
backlash. But, I am speaking of commerical threaded rod. if you use
a better quality screw, you should be able to get away with less.
As for slide blocks, Delrin is again preferred and pretty common.
Dave
> Hi,There are a few considerations. If you use plastic and spin too fast
> I'm new to the list and just about to start building my first CNC
> machine.
> A lightweight 3 axis machine for working circuit boards and foam for
> lost foam casting.
> I wondered what others did for leadscrews.. To keep the cost down, I
> was thinking of buying a threaded shaft and then using a section of
> shaft as a core, usng my injection moulder to injection mould Nylon
> Split Nuts. I found some shafting on eBay
> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?
> ViewItem&category=64819&item=7518353592
> or am I losing so much by using plastic nuts that I would be just as
> well of with cheap studding?
> The same method should be ok for simple slide blocks for the ways.
>
>
> Thoughts? is this a crazy idea ?
>
> Chris (-=Spiyda=-)
you can heat the stuff up and have a mess. Not sure how fast that
would have to be though.
Delrin is the plastic most people talk about.
The shafting you listed appears to be ballscrew stock in term, but
also is listed as trapezoidal so it might be ACME. not sure.
One thing you can do is to grind an end to is acts like a tap.
My experioance with threaded rod is that the surface is rough and will
tear up the plastic. I put my screw into the lathe and spun a die
over the length to remove any dings.
then with my thumbnail and some paper towel, I ran it so my thumbnail
would thread itself along the length. every time I hit a rough spot,
I used a small file and removed the roughness.
I repeated this until I could go from end to end with no roughness.
As for plastic nuts, the goal is to have about 20 threads engaged.
Only a few threads will allow the differences in peaks to effect the
backlash. But, I am speaking of commerical threaded rod. if you use
a better quality screw, you should be able to get away with less.
As for slide blocks, Delrin is again preferred and pretty common.
Dave