hello tf the 200x100 had a 5mm wall but i never used it for the y and went for 150mm box in the end,i just made those wedges with the 200x100.
well most of it done,a pal did the work on the aluminium plate,chuft with how it turned out,
just a few more bits to get, i was going to fit the x rail to those two bits of box section but after a bit of discussion ive got my eye on some thick tool plate steel bars that i,ll bolt to the table instead,
Wow nice build, I've been wanting to build a fixed gantry machine. Looks great 👍👍👍👍👍 keep us posted.
Thanks mike
Im almost there with it now,ive got a sort out the belt/pulley assembly for the x screw..put a few holes in the frame,and get everything square,
ordered a pc which should be here in a few days,
So much for smashing this together in a couple of weeks,never works out like that.
Im looking forward to seeing how it performs but i half wish id just bought an old vertical mill and converted it.
Hi, I like your design......very similar to the ToolCrafter of Indian origin, except that one is a commercial job and made from cast iron castings.
The consensus of opinion is that without stress relieving you'll get some frame warping as it settles.....is that why you mounted the table rails to angle brackets on solid beams and not bolted directly to welded pads on the frames?
With a build of this nature I'd expect it to be very capable of milling steel.
Looking at the first pics of the two columns I was at first dubious as to the rigidity of them to resist deflection from cutter load, but with the subsequent addition of the two wedge sections I think you did right.
Here's a pic of the ToolCraft model that triggered my interest in a fixed gantry mill.....note the linear tool magazine at the back.......so simple to access.
Ian.
Last edited by handlewanker; 02-19-2013 at 09:22 PM.
Thanks for your imput HW
With the rail and brackets i would have had the table/x rail ground also but due to one of my many lapses of concentration during this build my impatience ruled that out when i welded in the gantry up rights.so there that way as a consequence rather than planned.
Otherwise heres the machine that ground the y axis face,it would have been ideal with a capacity of 48 inch across corners to do the table,but given the comments of warping over time (something i hadnt given a thought to when i set out)im a little more happier with the bracket idea,
Reading your post i wish i had put down some 10mm thick steel plates for the brackets to mount onto rather than go right through box section with long bolts..hmm
I like the machine you linked to,ive seen the image several times but didnt realise they were cast construction.
Lumsden Grinder used
Last edited by shoot; 02-20-2013 at 12:26 PM.
Hi, I saw that machine on another post somewhere that refered to fixed gantry type mills and it took a lot of sifting through the websites to get the name of the company and place of origin.....purely as a matter of interest.....I am slanted to the fixed gantry type of construction and away from the moving type...lots of issues there when the alluminium moving gantry type were investigated.
I assumed the rail mounting method you used was "planned" due to having the columns welded to the base........in the design I have in mind, I considered the welded column to base option and contemplated hand finishing the rail mounting pads, but am now thinking that a bolted to the frame method for the columns will allow machining to take place.
It does mean that a 10mm thick pad must be welded to the frame to bolt the columns to and prevent the tube from flexing longitudenally under pressure from the cutting forces, and your method of adding the wedges to broaden the column base is the way to go.
I prefer the idea of modular construction, IE, base, columns and crossbeam as seperate items, after a lot of thinking, and as square tubing has no integrity in the side plane and can flex like a spring, additional bracing would have to be introduced by drilling holes at the corners of the tube and welding 12mm diam round rods from the outside to form internal triangular bracing.
It's quite an easy job to drill holes at the corners of the tube and weld the rods (12mm diam) in from the outside and it does brace the tube proportionately and exponentially to the number and placement of the rods.
I think internal bracing with welded rods is far more effective than filling with epoxy granite etc which will only dampen any resonant vibration but not prevent the tubing from flexing.
A casting would have thick walls compared to square tubing, and I don't think square tubing comes with 12mm thick walls, which means if you used 12mm thick plate and welded the sections together to form the boxes, you'd have the equivalent of a casting without the flex or need to weld extra pads on, and that's a lot of welding.
In the final design I would like to have double ball nuts for the 3 axis, to prevent any backlash whatsoever.
The Chinese alluminium gantry routers sold on Ebay do have ball nuts on some of them, but as the ball nuts are single type they will eventually have backlash.
This is all very hypothetical, but you must plan to go in the right direction before cutting metal.
BTW, anytime you have to go through a box section with bolts it's better to drill much bigger through both sides and insert a solid spacer welding in both sides from outside, then drilling and tapping for the bolts, otherwise the box section will crush as soon as you apply a load and getting spacers down the tube is well nigh inpossible unless you anticipate the need and weld them in before the base freme is welded up.
Ian.
Done,ive just got to sought out the usual allignment issues (spindle) tidy the wiring and hoses otherwise im chuft with it,we had it cutting scrap aluminium plate a 3.5 doc yesterday big chips flying everywhere,(i,l have to mount some perspex screening to the sides) but a far cry from the 0.2 doc i had to live with on first machine i,ll get a video up soon,soon as i can find something interesting to cut,thanks all
Last edited by shoot; 03-03-2013 at 01:36 PM.
Congrats--looks great! That's quite a step up (or down!) in DOC!
David Malicky
Hi great build and so quick too.....love the colour scheme.
One question, when you mounted the Y axis rails (under the table to the tool steel rails), how did you allign them, that is on the top faces?
You would have had to have a large surface plate or mill table to get the two rails running dead parallel.
I think it would be fairly easy to measure across the width of the rails at both ends to get them parallel, but how did you allign them on the top faces?
Ian.
Sorry for the late reply handle ,i used to get an email notification...thanks and rushed would be the word i'd use,yes i used a big slab of tooling plate.
The plan is to pull all that Y axis off (we call it the X here), and do what i should have done in the first place and that is put but down a large lump of tooling plate with with the necessary chanels and cut outs to cater for the profile rail and ball screw etc i will also go longer on x axis(y) by around 300 or 400mm replacing the rail and screw.
scuze my ignorance ... but surely the gantry should sit in the middle of the table ?
Its made that way so the cutter is inline with halfway point of the rail .Originally Posted by Bl@ckrat
Hi, it doesn't matter where the gantry is positioned as long as the spindle can reach the table for it's entire length.
This is just a positioning thing due to the offset that occurs with the spindle carriage mounted on the X axis (crossbeam).
As long as the spindle is in the middle of the table when the table is in the middle of the rails, that will give you equal coverage both ends.
That is also why the gantry side supports are cranked like a dog's back leg instead of being straight up to reduce the overall length of the router base frame.
Ian.
Aaah okay , it just looked like the table would be off the rails before the spindle would reach the end of the table
Consider for a moment a more conventional mill like a Bridgeport, you can't reach every corner of the table on those machines. We are assuming you won't be rotating the head. The point is you don't need access to the entire table to have a useful machine.
That being said there are advantages to designing your machine to give you 100% table coverage. Usually getting this complete coverage requires a few design compromises. For example in a moving gantry machine you may have to extend the X rails beyond the "table" part of the frame. For some uses it can be an advantage to be able to machine past the end of the table.
It allows you to use the spindle to get the table perfectly flat.
My router has a table that is larger than the travels, so my flat part is pocketed in the table itself. I use fixture plates that sit in this pocket, so it doesn't become a problem, but I could see how it would be a problem if you needed to do extra large parts.
Lee
Re: Fixed Gantry CNC build log
sorry folks for not getting back to this.the build was probably over kill for what i needed,but fun all the same.
heres a naff video with crappy youtube music,feeds n speeds were a little on the low side,but if i remember right i was still playing..trying to find the that sweet spot with the cutters i was using and delrin.i think here it was 6mm single flute carbide.thanks
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