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That is basically everything I need apart from a two relays. I'll be modifying the 24V distribution system a bit.Quote:
Originally Posted by Noplace
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That is basically everything I need apart from a two relays. I'll be modifying the 24V distribution system a bit.Quote:
Originally Posted by Noplace
Nice work looking great Chaz . . .
Thanks. Trying to finalise the based / gantry design now so I can I complete the moulds and start to pour concrete.Quote:
Originally Posted by routercnc
Where did you get your concrete from?
I'm making my own using 52.5R cement, Basalt Stone, Sand and super plastifier.Quote:
Originally Posted by Fenza
What super plasticizer are you using and where are you getting it from?
http://www.concretecountertopsupply....turesPozzolans
Is the best place I've managed to find.
I dont know the make. Im getting it from the guy in Germany where I buy the rails and other stuff from. It wasnt cheap, he works in the industry so largely trust what he supplied. Ill try find out.Quote:
Originally Posted by Fenza
Hi Chaz
just thought i would mention this, regarding the build up of your reinforcing structure.
Years ago i built a trailer and installed bosses into the box section to support the tailgate, machined/drilled and first tapped the holes in the boss with the intention of finish tapping after they were welded in to the frame.
The carbon content of the steel used for the bosses was unknown and as it happens must have been sufficient to harden the inserts, i was unable to finish tap the holes after welding and had to cut the bosses out and remake with mild steel, so make sure your rail supports are mild steel and even do a test piece to make sure.
Good luck
Mike
Thanks. In this case, there will be no metals 'sunk' into the structure.Quote:
Originally Posted by mekanik
Mounting will be directly onto the concrete however there will be a layer of DWH 'epoxy' to provide the flatness needed. The nuts will put into place after the structure has hardened and will be held with epoxy.
Hi Chas
Sorry but i can't get my head round how you are going to fix the rails to the concrete or set the rails perfectly straight and co planar prior to injecting the epoxy, could you run through it step by step (for a dummy)
Mike
Sure. It's probably a slight different way to do it, but Ill try and explain as best I can.Quote:
Originally Posted by mekanik
1. Cast the concrete, try and get it reasonably flat. Is it 'good enough', no.
2. Clean the concrete, grind the area to prepare for the DWH putty (or liquid, there are 2 options).
3. Place the putty along the location where the rail will sit (so in my case, roughly 50mm wide x 2 lengths).
4. Place a reference surface against the putty. The reference surface has to be perfectly flat (well, to whatever tolerance you need / want). The reference surface should have a release agent so that it does not stick to the putty.
5. Putty dries, remove the reference surface, the putty is now hard and has formed against the reference shape.
6. Either drill holes or remove the material used to block the holes (wood in my case). The putty would have cured over this.
7. Epoxy the M12 nuts into place, using the rails in location and putting a release agent around the bolts and threads of the nut.
8. Wait for the epoxy to cure, then tighten up.
The 'key' here is the reference surface. This has to be perfect. Ideally the X and Y are done by the structure and at the same time. Im still working on how best to do this. I have a granite surface plate which Ill likely use. I can make some surfaces on my mill (perhaps not as accurate) or I can cast putty against mild steel which is then 'correct' against the granite surface plate which is then in turn used for the machine.
Here is a vid of similar. They use a putty, drop the surface onto it. This is moglice .... not the same, but the principle is the same. The putty will form a 'perfect' copy of whatever you place against it and its as hard as concrete once cured. Its fairly expensive stuff. You also get it in liquid form which can be poured between two surfaces.
https://www.youtube.com/watch?v=BZuEH4nyBtw at 4min35 you will see what they have, once they lift the top surface, is a perfectly aligned surface. Once cured, its as hard as the concrete and has a similar hardness rating.
https://www.youtube.com/watch?v=dKdanHZmV_k this is a similar idea. The key is to have the 'master' to reference against.
Electrics now mostly done. Running 2 of the 3 axis in the video below. I'm missing a plug needed for the 3rd drive but all tested and runs. I still need to wire up:-
Spindle (when I decide what Ill use)
Limits
E Stop etc
Some pics below showing the 'mass' of wiring and what it looks like near completed. Still need to remove the white protective cover from the plate.
https://www.youtube.com/watch?v=RLCvlyi4Z_E
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Starting to finish off the mold for the first casting as well as one of the bearing holders for my Y leadscrew.
The part was flipped over as its 50mm deep, my probe doesnt have the best accuracy so there is a 0.2mm or so step, doesnt affect the part however.
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Managed to pour the mould today.
Some lessons learnt.
1. Make the mould stronger.
2. You use mix than you expect .... dont ask me where it all goes.
3. It's tedious .... just stick with it.
Here is the mix (0.2 water / cement) mix without superplastisizer.
https://www.youtube.com/watch?v=2IeEhFW44F8
Add some magic juice and it changes completely. Just to make it clear, the mix below has no more water, just 1.25l of plastisizer.
https://www.youtube.com/watch?v=4KfWcawy7b4
Just checked the pour now, still very liquid. One of the boxes moved but as it wasnt set yet I was able to fix it. Hoping that it will harden overnight.
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Hi Chaz
I hope this is going to be OK, the cross section is very thin and if you haven't placed rebar in that lot i envisage problems(hope not)
regards
Mike
Hope so too. The main section is fairly thick (200mm), the ribbing is for extra support. Those are 50mm wide.Quote:
Originally Posted by mekanik
Have you got any images of the final design you settled on Chaz?
50mm thick UHPC is pretty strong! :beer:
Ill upload some. I need to rethink the gantry. I need to use less concrete. The plastisizer cost a fortune ...Quote:
Originally Posted by Fenza
The ribs won't add any strength without rebar. the mix for small cross sectional beams/lintles ect is 3parts aggregate(10mm) 2 parts sharp sand 1 poart cement. but you still need the rebar.
i feel really bad about this as i should have mentioned it earlier.
But you seem to have gone into it in detail as you have with the rest of the build.
Mike
http://www.moertelshop.com/PCE-Flies...uenstig-kaufen
Polycarboxylate is the normal liquid superplasticizer. The shop I just linked seem to be pretty good and reasonably priced.
I'm going to try them out for some of my own experimentation.
Cheers,
Fenza
No problem. Lets see how it holds out.Quote:
Originally Posted by mekanik
Looks similar to what I am using but mine is a bit lighter. Same idea however.Quote:
Originally Posted by Fenza
Chaz is the colour from the super plasticer or have you added pigments.? Also expected that you would have added fibres.?
Jazz, the cement is white. Snowcrete (basically). The stone is black and the sand then, well brown. The plastisizer is a light colour .... I suspect most of the colour is the mix of sand and cement.Quote:
Originally Posted by JAZZCNC
I did not add fibres. It was discussed (with the guy providing me bits) and in his past experience it was pain to do and he did not feel worth it.
Erm not sure I've mixed plenty of plain concrete and it doesn't go that colour. Think something is having an affect.? maybe because less water.?Quote:
Originally Posted by Chaz
Erm that surprises me because most of the polymer concrete bases I've seen have used fibres of some kind to bind together.?Quote:
Originally Posted by Chaz
What cement did you use? Normal grey stuff?Quote:
Originally Posted by JAZZCNC
Ye just normal portland cement and to be honest looking again I think this cheap monitor I'm using is probably some of the reason it looks funny.!!!Quote:
Originally Posted by Chaz
Lol. Ye, the 52.5R stuff is whiter than the white we are typing on here ....Quote:
Originally Posted by JAZZCNC
Stolen from someone's website. These are walls made from the same stuff. Colour is similar.
http://www.landspacedesign.com/wp-co...03-705x468.jpg
Probably why it's called SNOW Crete then. . LolQuote:
Originally Posted by Chaz
Id guess its related. Its used extensively for architectural concrete work.Quote:
Originally Posted by JAZZCNC
Some progress. Have removed some of the wood to see. Nice clean finish, no air bubbles (as expected with the plastisizer). Struggling to get the wood out, even with a mold release agent, its too tight to come out.
I need some advice on sizing some metal. I want to build a frame below the concrete to hold the mass and allow some castor wheels to be mounted. Estimated weight will be 2000kg when done. Can anyone suggest what size mild steel tube I can use?
Thanks
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You could always build the frame out of UHPC as well. Just a thought :beer:
What happened to that rod in the first photo?
Fenza
I could but I think its easier to weld something up quickly.Quote:
Originally Posted by Fenza
The rod was some material that went into a pipe I was trying to use for a hole in the mould. It moved and filled with concrete, so thought that Id cut it open and inspect (once it had dried).
If it was me i would use 100x100x4 and make a pallet from it. For me this is the ideal profile big enough, easy to cut at home, strong enough, cheap enough, ... . however reinforcing plates where the wheels are.
Just need to drill some holes into the bearing holder, quick test fit. Have bought some reference surfaces (surface plate for the table) and also a fairly large box (engineering type, flat within 5 thou) that Ill use to cast the DWH against. I was going to try something cheaper but its risky and this will be better.
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Quick update, been slow as I have been ill.
Getting ready to place the putty for levelling.
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Chaz
Would you mind telling me the mix that you used ie cement, stone, fines and the water content byr weight or volume
1/3 rd equal parts of Cement (52.5R), Sand (Sharp Sand, 0-2mm) and Basalt Stone (6-10mm). 20% Water volume based on Cement used (so in this case, 5 litres per 1 bag of 25kg each above).Quote:
Originally Posted by Clive S
Thanks for the info are you using any SP (superplasticising) like modified polycarboxylateQuote:
Originally Posted by Chaz