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Hello,
I thought i would post a bit of build thread for any body interested and perhaps i could possibly garner some help along the way.
The original machine has some history on this forum and others.
It was this one: http://www.mycncuk.com/threads/4533-...ht=multicutter
I purchased it from a company in Nottingham and it was in quite a sorry state when got to it. Just a few pics to fill in the history:
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Anyway i thought even if i just use it for the chassis and replace everything else it would be a good candidate for our first starter machine. So did the deal and went back to dismantle it and get it out...
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Home:...
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Quickly skipping through trying not to bore you too much We built the machine back up and sorted some of the glaring issues.
Encoders were hanging off the layers of stacked mdf so fabricated some new mounts in metal. A new controller was needed. We put all new wiring throughout and tidied it into an electrical cabinet. Shortly after getting it running the spindle died so I had to buy a new spindle and vfd for it.
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After a year of use and learning the ropes I have discovered the limitations of the machine. The old DC servos are very slow. Im lucky to cut between 1-2m per min and rapid at 4. I dare say the drives could tune up a bit better however i doubt there is much more performance to be found.
Despite the machine being very heavy made from big sections the sheer size of it is causing its own problems. The 3 main rails that run front to back that hold the bed up are bowed like a banana. Also I think the construction is causing a nasty vibration on certain movements which is showing in the cut finish.
At this point i think its the best call to cut our losses with this machine and build a new chassis of a better compact size. New motors are a must. I also like the look of the UCNC software.
The current machine is blessed with a lot of thick walled steel section. Plus the gantry including the end plates etc seems very solid. My plan was to use what i can off the old machine and rebirth it on a new chassis with steel reclaimed off the machine reusing the gantry at a chopped down length plus some other bits like the carriage.
So...
Started cutting the steels for the legs / base. These are 3'x3'x1/4.. its all in american money as this machine is from the states originally i believe (roughly 78x78x6mm in figures that mean things).
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Then some of the biggest feet i could find. These are 180mm dia and rated to 3tn apparently on a m20 thread. I cut them down and installed them in a nut welded to the bottom of the base legs.
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The bed for the machine will be welded together but i wanted to be careful where i applied heat. I've bought some pretty chunky steels for the main rails 200 x 150 x 8mm. Theres about 200kgs in each piece certainly wouldnt want to drop them on your toes. They were pretty straight but i didnt want to risk turning them into an expensive heavy banana so i thought it would be best to bolt them down to the base structure. I made some brackets and bolted them on with m20 bolts.
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Here they are bolted down and everything leveled up as much as possible.
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That was a couple of weeks ago. Today i got onto cutting the cross members for the bed and tacking and welding those in. These are 5x3x1/4 and are spaced roughly 600mm apart. Hopefully this will give enough support to the router bed.
With 6 pieces each with 4 joints i have 24 opportunities to practise my uphill welding technique...
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Full day on it yesterday.
I chopped down the main big steels to size. They are 3.55m long now which hopefully means i can get a full 10' sheet on the bed and have room to park the gantry over a linear ATC at the back of the machine.
We added some 80x80 steels in between the main cross beams to further support the router bed.
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Then i went to work on the box section which will form the base to build off for the side Y rails. I did this in some 50x50x5 rhs box section. I mag drilled the section with 22mm holes on 3 sides of the steel and then band sawed through the corner between 2 of the holes. This is going to form a little access hole for some fixings. I also used it to plug weld the 3rd hole to the main large steels after getting it as level as possible.
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Looking good, may as well weld the "pretty chunky steels for the main rails" after all, cant see them moving shape any more than they already have from the bed cross sections...
Good to see your sorting her out tho, thanks for sharing!
Im not too sure they are well fixed down to the base with m20 bolts any.Quote:
Originally Posted by Lee Roberts
My worry wasnt the bed cross sections as they are all welded on the horizontal plane and then they are also all holding each other from moving too much. It was heat in the top and bottom of the rails that i was worried about the steels bending on the vertical plane.
I welded the side rails on to the big section and as it was bias towards the very bottom of the sections they took a little bit of the weight off the 2 end feet.. they went from not being able to rotate by hand in a million years to getting half a turn on them.
Yesterday i shuttered in down the side of the rails and built a moat on both ends by cutting a piece of box section in half. I just used some vhb tape, some stainless strips we have for letter building and loads of hot glue to fill any gaps.
I then poured the west system 105/209 in to level the rails together. I calculated about 5kgs+1.5kgs for an area about 11000mm x 50mm to a depth of about 10mm. i mixed and poured it in 2 batches.
The next 20 mins i watched im amazement as the plan all started to come together then panic set in as the mixture despite its viscosity was managing to weep between the rail section and the main sections. I tried to cover it up as best as possible and then accepted it would be fine as it was only very minor and would stop soon.
I went to sleep last night wondering if it was going to be all over the floor come today... and success it wasnt!...
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Haha, glad you got away with it.
I also learnt that lesson...
It's best to use something to seal the mould. I used 5 minute epoxy selectively applied to the mould line and corners.
Hopefully the epoxy works out for you. For me it was not as good as I hoped but I didn't pour it so thick and so it may not have leveled as well.
I am my own worst enemy.. for a whole 2 hours in the lead up to pouring i just kept saying to myself... i should probably just stick a line of hot glue or sealant between the 2.
Then when it started dripping i just kept saying to myself... see i told you it would of taken all of 2 minutes and now look at you.
Its leveled amazing at 10mm you can look down it and it looks straight as anything.. my only worry now is that it goes off hard enough? I've currently got 10mm of very stiff jelly for some rails. Surely it will be fine lol.
It might take 8 days to harden fully depending on the temperature
So i read... now ive just got to spend the next week making sure people dont keep sticking their fingers in it
Really it's been too cold for pouring epoxy and I'll be surprised if it hardens properly. I wouldn't touch it for a minimum of 2 weeks, don't even remove the moat or anything just leave it alone.
The workshops are heated mate it’s well toasty.
Expensive but toasty
But no I’ll just leave it alone as long as poss
Did you leave the heating on overnight.?Quote:
Originally Posted by BigBrand
Still, at 10mm Thick, I wouldn't touch it for a minimum of 2 weeks. I usually pour around 5mm and leave 2 weeks so I wouldn't go near this for 3 weeks.
What happens is that the outer layer will feel set solid but the middle is still soft and if you try to fasten rails to it too soon they will sink, this doesn't always happen straight away but over a few days the torque on the bolts slowly sink the rails.
Sound I’ll plan for at least 3 weeks then... that should give me enough time to sort out all
The other bits and pieces. Am I still ok to come grab those bits and pieces at some point?
Yes, I'm around all week, just let me know before you set off.Quote:
Originally Posted by BigBrand
Change of plans. Im putting all new on this build so the big thing is up for grabs if anybody wants it...
http://www.mycncuk.com/threads/14380...373#post123373