Hi Boyan, thanks for the advise. I looked at the design again and the main areas I think may cause me some headache are lining up the x axis bearing supports with the gantry sides (as clearances are small) so guess there will be a lot of back and forth with the hand file for this, and another area was the ball screw bearing support depths on the x axis being difficult to line up without a mill, so I reduced these in width and made them into spacers with thru holes instead (nut/bolt onto box section), allowing me to again skim them down easily with a file if required.
Also, I noticed that I could extend the rails on the x axis all the way along the box section and reduce the length of box section to better utilize the full length of the ball screw, so the X axis rail is now 1050mm. Front hard stop was easily added with a bit of 50 x 50 box section but for the back, I used 10mm plate as anything over the back face would get in the way of the belt. Not sure if this will be enough?
For the carriages, should it be 'ZA' pre-load? Also how do you define the longer carriages in the part reference and what is the length of these so I can double check the models please?
Yes, ZA preload. BST Automation aliexpress, Fred if you have not figured the provider. You could use my name as reference and he will give you the right prices. Most of the people here buy the stuff from him. Alsmost always he has the best price and most importantly packs very well and stands behind if there is an error or fault
Hard stops also could be 4 big bolts or small plates welded at the sides that the plate that attaches to the ball screw hits them at end of travel. Your looks ok, just dont like the plates at the back of table, better as in front- box section.
The main mission of the hard stops /according to me/ apart of stopping the machine travel, is to stop it at that moment say just 2cm before ballnut travel ends. They must be nearly as possible square as i mount there the limit switches and they are my reference of squareness. So i use straight edge and make them truly square and weld them at the end when gantry is mounted and squared. If you understand what i mean
So i see the real beauty when the machine frame length or say distance between hard stops at the end of frame is = (desired travel) + 2cm
where travel = ball screw length - length of the gantry legs) + 2cm
So i know i have not wasted spinning mass that does nothing
The Following User Says Thank You to Boyan Silyavski For This Useful Post:
Boyan - Thanks for the advise, I will look into the distance and confirm the 2cm as per your comments.
Are there any advantages to using the longer type carriages? Models are based on the shorter ones 'CA', and using the longer 'HA' type carriages will further reduce the cutting area.
Last edited by examorph; 01-02-2016 at 02:11 PM.
I also want to be cutting aluminium, so updated the models with the longer carriages (CAD models from here) and replaced the rear hard stops with large bolts (will use a steel plate spacer on the inside of the box section to support these). One thing I cant figure out is if I was unlucky enough to hit the hard stops, would it not end up distorting the frame and cause more problems?
Anyways, the larger carriages didn't make that big of a difference to the work area and seemed to fit OK with the existing setup (slight overhang though) so all in all, seems to have worked out ok.
I have shown carriage spacing for each axis. Can I reduce or need to increase it anywhere?
Do you guys thinks i'm now OK ordering in the linear components? If so, hoping you could help me with a few things:
Linear Rail -
2 x Hiwin HGR20- 300mm linear rail
2 x Hiwin HGR20- 600mm linear rail
2 x Hiwin HGR20- 1050mm linear rail
12 x HGH20HA ZA Hiwin block
Do you normally tend to specify the accuracy and dust protection indexes as part of the carriage/rail refereces when ordering from Fred Lee?
1 x SFU / RM 1605-L250mm Overall length- C7 ballscrew with a ballnut with end machined and increase dimension F on end machining to 30mm for pulley
1 x SFU / RM 1610-L650mm Overall length- C7 ballscrew with a ballnut with end machined and increase dimension F on end machining to 30mm for pulley
2 x SFU / RM 1610-L1050mm Overall length- C7 ballscrew with a ballnut with end machined and increase dimension F on end machining to 30mm for pulley
4 x BK / BF 12 support for ballscrew
If you spot anything out, please let me know.
Last edited by examorph; 02-02-2016 at 11:14 PM.
Personally I would specify the F length to be 30mm ( you can always cut it shorter)..Clive
examorph I forgot be very clear when you order the screws that that you quote the total length of the screw including the F length. ie. 1605-L250mm including F=30mm length .
If you decide on the extra 5 mm don't forget to change your sizes..Clive
Clive - Thanks for the advice and the heads up. I have updated the original post (#36) to show the 30mm length, will just send a copy of this to Fred Lee when ordering. One thing I am not too sure about is, do they cut this from longer material stock and give you an "extra" Xmm on top of the standard amount or do they just machine back the 30mm and as a result, reduce the original screw length?
Also, any advise on if you normally specify the accuracy and dust protection after the carriage ref ie, HGH20HA ZA C SS ?
Last edited by examorph; 02-02-2016 at 11:21 PM.
The overall length = the end for the BF bearing then the screw part then the BK bearing including the threads and the F length So L = the total length .
Ask Fred for the quotation and he will get back to you very quickly usually within about 36 hours.
Edit I think you did alter the length but check
Last edited by Clive S; 02-02-2016 at 11:50 PM...Clive
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