Thread: First CNC machine
I know what you mean about just making it up, its so much easier when its there in front of you, than sitting at a computer with CAD. Have you seen the design guide for the blocks? looks like you will have to be careful with the spacing as any racking will cause them to bind.
Since they are 4 way loading have you considered putting the x axis rails on their side, that way you just need a flat plate to bolt the carrages to the y axis rail.
Where do you get the ali sections from?
Yea i have seen there website, i think you are suppossed to use one block without the side bearings, hopefully it should work ok though.
I have thought about putting the rails on the side but then there will only be one contact patch per block instead of 2, but putting them on the side would give me a bigger y axis. il see how it goes.
the alu profile is from RS
i have put the rails on the side, and its made everything alot easier,
i have made a design on autocad and started to roughly make it out of steel, as you can see not many holes line up lol.
im currently waiting for some 45x45 alu profile and the plan is to have two vertical sections bolted onto the alu side plates then, two long pieces across forming the y axis. im also planning on mounting the y axis motor on the inside and using a pulley to attach to the screw that will go down the middle of the y axis.
Looking good. with regard to the rails being on their side with only one contact then in dosnt matter as in reallity you are only supporting the weight of the y and z axis. The plunge of the z axis will counter some this and you will then have max strength (4 contacts) in the sideways movement of the x axis where you need it to counter the cutting forces.
Not sure it I would have moved the y axis rails as well tho. For that long travel on the z you need them as far appart as poss to reduce the moment, the other side effect is that the y rail has moved the spindle futher way! You might want to shift the y axis rail back a bit further to compensate, dosnt mater if the motor overhangs a bit. mind it would be easy the remake the side plates later if it dose cause any problems. (Chatter, binding etc.)
Did you find RS the cheapest for the aluminium sections?
i put the y axis rails on the front as it keeps them a meter long and is alot easier to mount a plate straight on, instead of building a box around.
plus i may be using some low height rails instead, about 9mm instead of 30mm.
but ye i might have to move the y axis further over the rear bearing.
as regards to RS being cheapest? probably not but my work always gets stuff from there so its easy, i think it was about 20 quid per section,
the rails and bearings are cheaper than igus tho,
i got the 45x45 alu profile today, so i made the y axis, its rock solid with no flex, but i think the igus bearings may have to go as it barely moves on the x axis, so i may have to get some proper ball bearing carriages for the x axis and use the igus bearings on the y axis.
does anyone know where to get cheap rails and carriages?
Hi Kev, it' looking good - loads of progress...
I cant help you with the rails & carriages (I made my own), but I like your whiteboard sketches! I do alot of thinking out loud on a whiteboard in my workshop... Can't beat it...!
Thats a shame, I didnt think you would have a problem this soon.
Is it binding because of the long distance of the y compared to the truck spacing or is it just the weight causing excesive friction? If its the former then it should disapear if you drive it with a screw on each side. (eliminate the racking) might be worth pursuing before for you make major changes.
For the rails I beleive Gary at Zapp sells the 15mm rails and 4 way loading trucks for the same as the Igus stuff you bought. £50-60 for 1m rail and £35 ish a truck. These also have way more capacity as well.
I took the y axis frame off leaving the 2 plates on, and if u put any slight sidways pressure on the plate it locks the bearings up.
It could be due to the y axis being so big compared to the bearing spacing.
Hopefully work should be ordering the 20mm rails and carriages from zapp, they should be alot better due to having bearings, and they only work out to be about 40 quid more than the igus set.
Im going to try the igus rails on the y axis where everything should be more square and closer together.
By therouterlady in forum Manufacturer NewsReplies: 0Last Post: 18-09-2013, 04:28 AM