Thread: Recommendations for Z Axis?
Hey guys, can someone please tellme some tips about how get an better Z Axis? I will start the build next week, dont know yet if use this chinese rails or wait until my new ordered HGR20 rails.
I think that will be OK the chinese ones because this machine will be used for MDF routing. and maybe made some aluminium pieces for my next build.
Here is my idea of the Z Axis.
Material is 10mm steel will try to drill it and bolt it instead welding, but not sure that can make precise drilling, dont have very good drill press.
Its the whole machine
Last edited by samsagaz; 21-07-2016 at 04:21 AM. Reason: Update the Z Axis
Wherever possible keep the cutter tip within the area inside the linear bearings, where that's not possible keep it as close to the area inside the linear bearings as possible.If you will not be swayed by logic or experience simply pick the idea you
like best, but ask yourself why you sought advice in the first place and,
for a simple life, perhaps consider not doing so in future
If you would like near perfect Z axis IMHO some Very important info:
1. As said above keep the bit tip inside the gantry legs bearings step spread, side view
2. Make the design so that the rails are mounted on the moving z plate and the bearing blocks are fixed. Opposite to what you have done, not that what you have done is not valid for small Z travel.
3. Idealy bearing block spread on Z and on the bearings that move the Z left right / X/ will for same squares, or at least same rectangles, and ideally would coincide exactly on top.
4. A must for my designs is that the spindle is mounted so/ 2 brackets/ that it fortifies the front bearing plate in all positions, including fully extended / especially fully extended/
5. Use square supported rails on Z at least, best Z and X at least. Even better on all machine. 20 size.
PS. Square supported rails don't care how they are mounted. Not so with the rails you have chosen. Ideally on gantry top and bottom, left and right on Z. Your drawing uses them in their weakest positions.
I know you asked about Z axis, but I would not use that design for the gantry sides. That I-beam is very weak when used like that and it will just twist the flange for loads in the Y direction.
I would plate over at least one of the sides to create a box section. You could do this by extending the existing end plate on the end of the main beam so it reaches the bottom of the I beam (lower flange) and joining them.
I-beams can be used for the gantry sides but they need to be orientated so that the flanges are pointing up/down (not fore/aft) and the central web runs inside to outside.
So in top view it would look like this:
One more question.
I think that X Axis needs to move a lot of KGs/LBs i have 1150mm length 16mm rails and 1000mm length 20mm rails, and double and single blocks. Using the 20mm and double blocks will be an good upgrade, right? i think that the 16mm will not support very well all the heavy gantry.
Is possible to combine double and single block support in the same rail? if use two of the doubles i need to use an base of 220mm to attach the I Bean to the Rail Block, if use an double and a single one, i will need just 180mm
Show a pics to show what i means. (my english is not good)
Last edited by samsagaz; 21-07-2016 at 02:47 PM.
I've not used 20mm supported rail only 16mm. I don't know what the price difference is but I'd stay with 16mm or upgrade to profile linear rail (Hiwin etc.)
I don't see a technical problem with combining multiple blocks on one rail. Use whatever fits so single and double would be OK. On my new gantry it will have 4 single blocks per side. Spread them out as you have done so they are at the corners with a gap in the middle.
I meant to ask before - your X axis rails don't appear to be supported on anything. I would not rely on the lower flange which comes with the rail to give you the stiffness. It needs to sit onto a continuous box section or similar running the full length. That would also raise your bearings up and make the gantry sides much smaller, therefore making it very much stiffer for not much effort.
Yes, im fixing the X axis too, i think that will use an 50mm tubing but will use epoxy to level up and to add a few mm because the tubing that have just have 3mm wall and think that are not enough to insert the bolts. :/
Last edited by samsagaz; 22-07-2016 at 03:57 AM.
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