my build

[jonm]

this ali beam is becoming a source of many parts .... with the centre section cut out it makes a very sturdy motor mount






the skate bearing is in the mdf with another thrust bearing on the other side ... have some delrin may make a bearing block from that

[Ross77]

Looking good, those beams look promising. I,ve got some similar ones that are also from a stair lift. Not sure I would of cut so much out of it tho.

I plan to mount the rails on the other side with the T-slots, why did you choose to mount them as you did?
It will be interesting to see how it performs, save me some R&D

[jonm]

hi ross
even with the centre section cut out there is still no flex in the beam, also reduced the weight , it was very heavy... wall section is 6.5mm.
was intending to put a few 8mm threaded rods through from top to bottom , along the lenght, with 2 nuts inside and and 2 outside which would have held it rigid, also could have adjusted the preload on the bearings (as a adjustable spacer) but think its going to be ok. can always be added later

with the screw inside keeps the y axis and z axis very close , going to cut the centre section out of the z as well , to keep router as close to the y axis , to reduce cantilever

holidays start tomorrow so plenty time to rebuild

what type of rail are you going to use?

[Ross77]

Hi Jon
Fair play on the weight issue It seems that when you modify stuff you have to compromise, the removed section will reduce its strengh and torsional stiffness but as you say the reduced weight and the fact you can bring the leadscrew closer will probably be more benificial.

I'm just cautious now after setting up my lathe, it a fair old chunk of steel but it dosnt take much for it to flex and cause poor surface finish. I suppose it depends on what you are using it for.

My machine will be bit of a monster (stength not size) cus I want it cut seasoned hardwood and Ali. the rails are THK HSR 35's on the X axis and HSR 25's for the Y and Z. 30mm ground ballscrews and 750oz servos. just need the time to build it. :whistling:

[jonm]

ross
that certainly is a monster machine you'r planning , i am only using a trend t4 as a spindle , some sign making , engraving just light work , will keep a eye on your build when you start

to see how you apply the ally beam

[Ross77]

Unfortunatly its no. 3 down the list of machines and in the mean time I've got to convert a barn.........

My beam is slightly different as it also has T-slots on the side, so yet another option. I'm just looking at section properties at the mo to see what will work the best, as an engineer I'm a bit anal when it comes to calcs :heehee:

I'm still interested to see how yours works. From what I've found about much smaller beams and the fairly light duty you need I dont think you will have any problems at all. look forward to the next installment

[dickieto]

Hello i have similar alloy beam to yours found in my local scrappies got it for nothingtrue scotsman:heehee:(check out my thread if you want) any ideas what mines might be off of? any reason why you did not use rack and pinion system that was attached to alloy? i was thinking of using zero backlash pinion with rack,any idea what size motors i would need to move gantry 1200mm wide weight 14kilos
Tom

[Ross77]

Hi Tom
Yes I did see your thead, I will post on there once I can make the pictures bigger. Reply on your thread but what lead/ballscrews are you using?. i think the main response to your question is power... Belt drive and rack & pinnion require high power motors and give a low resolution.

With regard to identifing the beam, mine was easy as the burnt out chair was next to it with Stanna written on it...........

[jonm]

hi tom
the beam i have is from a stenna stairlift, found at the local tip
the reason i am not using the rack is i cant get pinions for it ,with (tribbles) help its mod 3.5 , which i cant find anywhere
also as ross said there are the problems with driving it , belts, some kind of gearing on the pulleys, to bring down resolution, more power needed

[Swarfing]

Give HPC Gears a ring, they will be able to source or make what you need. 01246 268080 or www.hpcgears.com