Thread: George's 8x4 router-me-bob
I URGE every body who's eager to build but don't have the funds to buy the right components now.!! . . . WAIT . . SAVE UP. . . I guarentee it will save you lots of money down the line but even more importantly make the build go so much smoother and save you lots & lots of heartache and sleepless nights.
Think the 2 rails is a definate then-!!
would you put them both on the front or as i have in my crude drawing- one top, one face?
also in terms of the Z axis, whats the best design you've seen/ would recommend?
was thinking of linear rail again, with a ball screw but could do with some pointers-!!
or is it easier/ more cost effectie to actually buy one?!!
ohh a bit of time on google turns out bought ones are hideously expensive-!
so now am looking for some (i assume) zero backlash ballscrew in maybe a 16mm? was gonna do 20mm hiwin type with the carriages fixed and the rail sliding to give more slide,
so i figure i need a motor mount, a flexi couple, the ball screw support, the nut, the nut housing, and the end support?
whats the best pitch?, and will 16mm be ok-
also anyone know of a supplier that has decent drawings/ downloads available?
getting there- only problem is work getting in the way-!!
Here you go George have a look at these. This is one way and my prefered way to build them.
The Obviously the gantry is not showing but the Y axis rails could go either way like I have them or both on front or 1 on top 1 on front but this way I prefer because it brings Z axis closer to gantry, increases travel and is very strong. The belts help with resonance and allow gearing up or down if needed.
I use 16mm screws with 5mm pitch, sometime I use BK/BF bearing blocks some times FF/FK just depends on what I'm building and have even been knownt tomachine my own blocks but can't be arsed anymore as the chinese prices are so low it's not worth the trouble.
These are just reference models so not 100% accurate regards alignment etc but all materials and linear rails, motors etc are the correct and actual size and match whats available.
Hope this helps.
The Following User Says Thank You to JAZZCNC For This Useful Post:
ohh nice drawing Jazz-
see what you mean re the linear rail placement/ getting the spindle as close as poss-
what reduction did you do on the belt-? 2:1?
saw one from marchant dice for £1400....!!
Thanks again for all your help- it's really appreciated-!
now that i basically know what i'm gonna do will do a bill of materials to see what the damage will be-!
There's no reduction it's 1:1. The main reason for the belt is to reduce resonance and also allow easier positioning, the gearing is just a bonus if needed.
The previous drawing shows the motor up high but I also make them with the motor reversed, it just depends on the gantry design really. If possible I use the other position as it keeps the centre of gravity lower(no big deal) and it looks neater. I'll let actual real picks explain they show it better, ignore the bracket that looks like num 1 thats machine specific.
Tip regards material be very carefull when selecting or buying the Ali plate that it's perfectly flat. . . It's often not.!! Often it's cupped across it's width or even twisted in it's length.
If you look close at the pics you'll see I machine all the bearing mounting surfaces. I do this for 2 reasons.
#1 It gives me a register for the master bearings and rail to butt against which makes setting rails parallel easier and allows for easy replacement/setup if stripdown/cleaning required.
#2 Very important.!!. . If you try to bolt rails or bearings to material thats not flat then you get binding in the bearings increasing friction and causing premature wear, if bad it will lock them up soild when tightening.
Linear profiled rails are by far the best for performance and longevity but like all high performance things are tempromental and in tolerent of shoddy inferior material or poor workmanship so therefore require higher accurecy.
If you don't have the capabilty to machine surfaces flat then I strongly urge you to buy ground flat plate like the ECO CAST from Alu warehouse it's more costly but will save you a world of pain and give much less friction and smoother action. This is what I do now as the little extra it cost's is worth the expense as it saves me many hours machining and I just machine insert pins for master registers and machine the edge.
Making one with linear profiled rails, 16mm ballscrew and 20mm ground flat plate along with pulleys etc will cost you around £310 and will handle anything you throw at it for millions of years at DIY level.
Skimping on a Z axis is just plane dumb IMO if you want a accurate machine as it handles all the cutting forces.!!
Thanks for those Jazz-
am looking into the pros and cons of using ball screw type motion for the x and y as well now- as it looks easier to set up than R&P-
so with that in mind does the panel agree that screws are more accurate/ easier to mount etc- ie less faffing to get the tension/ pressure on the rack/ pinion?
for the 'long' x axis (2500 ish) you'd just have the end block, the ball screw+ mounting block and the machined end bearing- plus the screw obviously-! (one set per side)
would you go straight on with the stepper or do a belt?
whose the best supplier for these- i imagine Zero backlash is what i'm after?
hope everybody's well
yeah i was looking at Jonathans post/ thread on this issue- looks like an interesting idea-!
is the problem that it can 'twist' in it's on length- or just it flapping about in the breeze getting its wobble on?!
my slight problem in this build will be the machining of the parts etc, as i'm yet to get a mill and lathe- but want.... hence my initial though of R&P.
i guess it's a toss up between the 2 as the ball screw method may be costly compared to a realtively cheap r & p...
keep going round and round and round with these decisions- sorry to keep asking pretty much the same questions over and over-!!
By Richard in forum Machine DiscussionReplies: 2Last Post: 18-02-2014, 03:18 PM