Thread: Let the fun begin !!! ???
it time to source linear rails, ballscrews , ball nuts , bearing blocks etc. so i'm looking for contact details for chai. i have found an email address for him but i'm getting no reply. i have looked at zapp but want to do a compare & contrast before i purchase. so if any body has his web address can they send it on?
please check your pm inboxSpelling mistakes are not intentional, I only seem to see them some time after I've posted
i have touched base with chai and just need to work out the 16mm ballscrew lengths. i also notice that the bearing shaft diameters for BK and BF are different and am curious to know why this is.
this is my z axis end view, it has 20 mm rails and a travel of 160 mm. i'm thinking of a z axis ballscrew length of 400+ 30 for for a timing pulley. i'm sure this is enough or should i go more?
I may be wrong but the BK end will have AC type bearings and the BF end will have a radial bearing they use a larger bearing at the BK end. Not sure if they make the ac bearings in the same sizes as the radial.
You will need to order the F measurement on the screw to be at least 30mm I think Chai standard is 15mm. ..Clive
The Following User Says Thank You to Clive S For This Useful Post:
So the BK bearing is 25mm thick (excluding the end cap and locknut) the BF is 20mm thick, so that gives a ball screw length of 355mm between shoulders. Then 12mm turned section on the BF end, 69mm on the BK end (E+F = 39+30). Total length = 436mm. You have to allow for the Z ball nut thickness , this will reduce the overall travel, I drew mine out using Sketchup to make sure I was getting the expected travel.
Also you might as well get the ball screw as long as possible because the price difference for a few mm is going to negligible.
I know it might slow the build but in my case I waited until the ball screws arrived before cutting metal. It was easy to size the metal to the ball screws but impossible the other way round if in error. That's one of the reasons I built the electrical panel first, waiting for the stuff from China.
Last edited by EddyCurrent; 10-08-2014 at 07:49 PM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Cheers Eddy, how long was the delay from Chai ? also did you get the ballscrews machined locally or by chai and if so would you recommend it? i might get it done locally because i have access to a lathe but if it's not too costly to get it done by Chai i might go that route but then i have read that some of the screws turn up slightly bent. i have used suppliers from china in a previous life ( job) and remember some of the parts delivered with poor packaging and very little protection ( not all suppliers ). it's very helpful to have the experience of previous builders who have gone down this route, hence all the questions!!!
I think it took 18 days from payment to delivery. The machining was fine, exact dimensions, good fit to bearings, far cheaper than anywhere else. Holding the ball screws in a lathe is not as simple as a bit of round bar plus they are very hard on the outer skin.
The parts looked okay until I fitted them whereupon I noticed some bending. I decided to straighten them myself and it appears to have worked well enough, it's all in my build log.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Regarding metal work, I think you have it sorted with respect to 3D carving, i.e. adjustable height bed, 4th axis option.
Have you thought about how the 4th axis will physically attach to the frame ? and will material held in the chuck be parallel to the X plane or the Y plane ?
I'm thinking about a 4th axis myself but there's no room in my control panel for the gear, but thinking about it I feel it would be best as a stand alone unit with control wiring back to the main panel via plug & socket.
Last edited by EddyCurrent; 12-08-2014 at 08:43 PM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Also one thing to take into account if your trying to get every last bit of travel out of screw is to allow for the bolt heads holding ballnut, you can easily loose 10mm depending on how tight you make it.
Regards the Z axis screw bearings then with screw being so short you don't really need one at the bottom if you want to keep cost down and it makes setting up that bit easier.
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By DarkWalkJRB in forum New Member IntroductionsReplies: 2Last Post: 07-02-2012, 07:31 PM