Giant 20' x 3' x 2' router build

I have decided to use a planetary gearbox for the x axis which will be direct drive on to the rack and also to use a spring tensioned mount for this. However i cant seam to find anything suitable alredy available unfortunately.

i have done a very crude mock up to get the ruff idea and to cheque for space ect.

Can any one give me any suggestions on how would be best to do the pivot on it, im thinking maybe i need some sort of sealed barring in there to keep it moving smoothly all be it hopefully only fractions of a mm.

Allso any other suggestions to the design that may be needed as i am pretty much just making up what i think will work from my head.

( sorry i cant figure why the pictures seam to rotate them selfs around)

I am just about to have the big wooden plates holding the z axis in the picture machined up in aluminium but wondering what thickness to go any suggestions? all the other parts i am having done will mainly be in 10mm but wondering maybe i should go higher for these to maybe 12 or 14 even

things are starting to move again i have just started to get some of the electrics together and things like the spindle is on order. I am all so in the process of designing a sprung motor mount for the rack and pinion and will be looking for some one to be able to machine it if there are any willing people?

i just got my 2.2kw spindle and mount through in the post and now have the task of fixing it to my 80x80 ali extrusion and was just wondering hows best to do it? The mounting flanges are a lot wider than the extrusion so im wondering if its best to tap the back of the mount and drill some holes all the way through the extrusion so i can bolt it from the back?

I would go with a Piece of plate same width as spindle mount fastened to extrusion with some nice strong bolts then fasten mount to that. This will make setup and tramming the spindle easier and backup the mount a Little.!

i did a little mock up in wood. In a aid to try and neaten things up i have taped some holes on the back of the mount and bolted it to the plate the heads of these bolts then actually locate into the slots of the aluminium profile then there are four bolts which actually bolt it to the aluminium extrusion using slide nuts. At the moment they are just m6 but i will change those to m8 when i get some larger slide nuts or tap some out.


Ps im not sure why all my portrait pictures get rotated to landscape?

Progress with the electronics! I now have working steppers motors and functioning home and limit switches, to many this is probably not much of a big deal but it was the most daunting part for me and with a lot of help from two very kind people who im sure know who they are i have managed to get the basics going.

https://www.facebook.com/photo.php?v...=2&theater

more progress today with figuring out how to fit the home and limit switched and and all so the drag chain to the x and y axis. More parts arriving tomorrow so hopefully i can make more progress.

I still have to sort out the rack and pinion drive system and i have to be honest i have been wondering about belt drive again.
any advice on improvements is more than welcome.

vfd mounted and the aluminium plates to mount the y and z axis carriages and steepers , its been a bit of a jigsaw trying to fit it all but getting there.all so run some trunking and a few other bits and bobs.

still waiting on a gearbox to do the x axis and now just got to order some belts and pulleys to get the drives connected.

what are the best methods for tensioning timing belts on to steppers. I have slots for adjustment but need some sort of screw type adjuster to get the belt relatively tight. Cant seam to find much on here.

Quote:

---

Originally Posted by charlieuk

what are the best methods for tensioning timing belts on to steppers. I have slots for adjustment but need some sort of screw type adjuster to get the belt relatively tight. Cant seam to find much on here.

---

Section 10 page 45.
http://file.lasersaur.com/docs-third...ming_Belts.pdf

I just used the same technique as putting an alternator belt on, stick a large screwdriver in behind the motor and lever it out until the belt is at the 'correct' tension, now tighten the bolts.

i guess that keeps things simple! the pulleys i have have two grub screws for securing however the shaft is totaly round, whats best to do there? put a flat for them or drill a hole or something? cheers charlie

Quote:

---

Originally Posted by charlieuk

i guess that keeps things simple! the pulleys i have have two grub screws for securing however the shaft is totaly round, whats best to do there? put a flat for them or drill a hole or something? cheers charlie

---

Use two grub srews M4 will do, these MUST be 90 degrees apart around the pulley boss (i.e. NOT opposite each other). File a small flat on the motor shaft for one of these screws only. Where the flat is, use a flat bottom grub screw, for the other screw grind it to a point so it digs into the shaft once tightened.

cheers many thanks thats great will get on to that

The way I have done mine is to put a copper plug (pad) into the grub screw hole. I have done this by using a bit of solid core earth wire from twin&earth cable just lightly swash it with a hammer and then cut a piece off that will fit down the hole so that the flat bit is on the shaft then just tighten the grub screws. That way you don't mark the shaft.
I have found that it is not necessary to put a flat on the motor shaft. ..Clive

Quote:

---

Originally Posted by Clive S

The way I have done mine is to put a copper plug (pad) into the grub screw hole.

---

Im sure the locknuts for my ball screw BK blocks had a grub screw arrangement like that.

Quote:

---

Originally Posted by EddyCurrent

Im sure the locknuts for my ball screw BK blocks had a grub screw arrangement like that.

---

Yes all mine did as well it's a common way of fixing as it does not damaged the shafts so that makes them easy to remove later if necessary. ..Clive

belts arrived, i had to go with 5 teeth less on the motors to get it to fit unfortunately well unless the belts stretch a fraction as it is right between sizes.

I mentioned it in a post earlier that i am geting a small amount of flex from the main back uprights which for the surfboards really isn't a problem as the load on the machine will be close to nothing cutting foam however i would like to try and reduce it as much as posable. I have been wondering about two options the first being bolting a pice of 90deg angle steel to each leg ( i cant get large enough channel or T section) and the second idea was to fill each of the current aluminium legs with a resin/granite mix or maybe even a concrete mix which i have been reading about which may help in other ways as well.

Can any one give any suggestions as to what may be best?

many thanks

any one got any ideas to the above?

Just a thought could you not bracket them to the wall? ..Clive

I was planing on bolting it to the floor i would prefer not to rely on the wall as it may well end up being moved else were were that may not be a option.

many thanks

Quote:

---

Originally Posted by charlieuk

I was planing on bolting it to the floor i would prefer not to rely on the wall as it may well end up being moved else were were that may not be a option.

many thanks

---

Bolting to the wall with brackets would be a quick simple fix. But if you have to move it so that it is free standing you might be able to triangulate the back of the uprights bit like an apex roof truss on end. ..Clive

Looking at other designs on youtube I found this one. Different layout approach which would be stiffer than your cantilever. Bit late I know, but any ideas from here?
http://www.youtube.com/watch?v=9zYrr4jNfWI

In terms of improving what you have - I don't think you'll get very far filling the back supports, or adding angle iron. You are looking for a big step change to make a difference. As Clive suggested either bolting to the wall or adding diagonals on each end coming forward to the front of the machine and onto the floor would be much better.

Can you post a picture of the whole thing now it is generally together? You might get a few more ideas . .

unfortunately due to the size of mine it cut down the options on design options as making a beam 20' long un supported would have been all most imposable.

I have all so seen videos of that design shaking violently when the router changed directions when cutting, im pretty sure mine is far stiffer that that design all ready. i Had wondered about bracing the ends but thought that possibly making the ends stiffer than the centre would be a bad thing maybe?

I will get a few more pics this morning showing the whole thing.

best regards charlie

Charlie I think mentioned before that you needed diagonal bracing on the lower frame and this would help your problem quite a bit but really your easiest option is the wall.
Personally I would brace the base along its length like the black line show and try it, but at same time a few brackets to wall would cure it easy. Then if you ever need it free standing then make some triangle supports (red lines) for it which go at the rear and bolt to floor.

Also becareful with those timing belts that you don't over tighten and pull the ends of the ballscrews inwards and cause them to bend or bind. The belts don't need to be drum tight just not loose.
Attachment 13085

i have posted a few more pictures bellow you can see i have all ready braced the corners of the table area which improved it a lot and stopped any movement in that area. I could brace it more underneath but i think the flex is coming between the top of the table and the top of the verticals. would filling the extrusion help with dampening any of the vibrations or flex down? would it be a good thing to do any ways?
I will have to maybe look into bolting it to the wall but i would like to see if there was any way i could improve it before hand using other methods.

I could probably put plates in the corners of the verticals above the table as well but they would have to be taller than wide so they do not interfere with things on the table.

I have adjusted the belts a bit and just pulled them hand tight before any signs of flex from the screw so will leave it like that at the moment many thanks for that info i was originally assuming they had to be pretty tight to work.

While we are here were is the best place to source the cable and steppers from as i am going to be needing a fare few meters in total.

best regards charlie

What's the thinking behind putting the VFD on the gantry as you can't change the speed etc. when cutting. ..Clive

Quote:

---

Originally Posted by Clive S

What's the thinking behind putting the VFD on the gantry as you can't change the peed etc. when cutting. ..Clive

---

He could be using the serial interface to set the speed, but either way it will be subjected to significant vibration from the machine, which is asking for trouble.

I have been advised that having a long lead to the spindle is a bad idea because of interference generated the vfd its is mounted floating on foam to dampen any vibrations, the speed will be controlled through mach3

It's true that problems arise with long motor cables but the manual for my 2.2kW vfd says it's okay up to 50m long before you need to add output chokes. Also it recommends that for minimum radio interference the motor cable screen should be connected to ground at both ends.

Quote:

---

Originally Posted by EddyCurrent

It's true that problems arise with long motor cables but the manual for my 2.2kW vfd says it's okay up to 50m long before you need to add chokes. Also it recommends that for minimum radio interference the motor cable screen should be connected to ground at both ends.

---

cool well i will see what its like when its up and running and decide from there, if there is a lot of vibrations still than i can easily move it, i think i could get it down to about 10-12 meters minimum but thats about it.

is there any suppliers for the cable you guys can recommend? is the stuff on ebay ok or should i go else were?
many thanks

Quote:

---

Originally Posted by charlieuk

cool well i will see what its like when its up and running and decide from there, if there is a lot of vibrations still than i can easily move it, i think i could get it down to about 10-12 meters minimum but thats about it.

is there any suppliers for the cable you guys can recommend? is the stuff on ebay ok or should i go else were?
many thanks

---

How about this:- http://quickbit.co.uk/cable/CY-cable...ble-1mm-4-core
I would earth the screen at both ends. Just search for CY cable. ..Clive

Cheers does the quality of cable vary much is there anything to look out for? the link you posted looks good. many thanks

Don't like Quick bit cable it is poor quality and it's brittle, prefer CSE cables and there's hardly any difference in price. http://www.csecables.com/acatalog/Fl...rol-Cable.html

many thanks thats handy to know i don't mind paying a little extra when its worth it. I am still having trouble deciding how to do this x axis and wether i did the right thing going for rack and pinion as i think it is proving a little tricky to fit it all in with the gear box and tensioning system. something keeps telling me i should maybe look back into belt drive as it gives more flexibility on were you can put stuff. If it was bet drive i could easily mount the motor above the x axis like in the picture or have it stationary on one end of the main frame.

i think we are really getting there now! i have picked up a cnc router parts pro rack and pinion drive for the x axis rather than using a gearbox at the moment, unfortunately it means swapping the rack to mod 1.5 so will have to sell the mod 1 stuff i originally got but it means i will be up and running sooner.

The cable has just arrived so thats all going in now however i just need to deside how and were it is best to situate the control box and the pc.

Is it best to keep the control box relatively close to the machine? whats the best way to protect it in a dusty environment? i was wondering about putting the box into maybe a kitchen unit type thing so it is double protected from dust and then have the computer some were less dusty but would be further away but being my first build im not really to sure what the standard thing would be on a large machine like this. Any suggestions would be great.

Well after a lot of fine tuning it's all levelled up and the main part of the build complete just the final wiring to be done this weekend and we should have some movement. I ended up adding some extra plates to aid setting it up and stiffening and also bolted it to the wall which made a huge difference

one thing I am still looking for are the caps to fill the bolt holes on the rails if anyone knows we're to get them or what I could use.

Many thanks

I have also got a full length switch to use as the e stop so you can grab it were ever you are along the length.

Very neat, looks great.