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Just make sure that if you're floor isn't level, it stays that way as if you move the machine the frame will distort slightly and in turn distort the epoxy slightly. That's why it's best to pour the epoxy with (ideally) all the machine mounting points (feet?) at the same height, so if you move the machine you can set them to the same height and be fairly confident of little movement in the frame.Quote:
Originally Posted by Clive S
jonathon you have confused me there lol :) if the floor aint level it means adjusting the feet so all 6 feet could all be at different heights depending on how bad the floor is. so when you say if the floor aint level it stays that way do you mean to have the machine to just be as level as the floor and leave the epoxy to do its job or did you mean what my badly made drawing shows lol.
sorry if im being a little dumb here.
cheers
ash
http://www.mycncuk.com/attachment.ph...id=15939&stc=1
id recommend caulk instead of silicone ... much easier to clean off
i tack welded 3mm flat bar for the epoxy bath , was super fast and simple to do with a tig welder
Your diagram is how I meant. You ideally want to make sure the frame sits such that there is no stress on it - e.g. in your drawing there are 6 feet and imagine the middle four were unscrewed so the frame isn't supported. The frame would then sag in the middle. If you poured the epoxy in this state, you would still get a nice flat surface, but if you change how the frame is mounted (e.g. adjust the feet, move it, add more feet etc), the frame will distort slightly and cause the epoxy to no longer be flat.
We're not talking much here - clearly the frame is quite rigid so wont flex much, but it's still something fairly easy to take account of which may help.
ok thanks jonathan, so basically before using epoxy make sure the machine is in its final place and all 6 legs are leveled and in there permanent position?
cheers
ash
At last:applouse:Quote:
Originally Posted by reefy86
clive i got an e in english 13 years ago i need to read a hundred times to your once lol :P
Not much worse than my C, 7 years ago!Quote:
Originally Posted by reefy86
Just spotted you're also in Nottingham - next time quicker to explain in person perhaps...
yes mate bulwell end :)
Hmm, on second thoughts...Quote:
Originally Posted by reefy86
http://www.mycncuk.com/attachment.ph...id=15940&stc=1
hahahahaha its not that bad :)
how much lean way do you have when drilling the rails? is it easy enough with just a hand held drill or does it need to be precised? all i have in my tool cabinet is a screw driver hammer and drill lol. im willing to buy tools as i go along with the machine so not too much of an issue if i do need some sort of new tool lol.
cheers
ash
Well as long as you have the hammer you will be fine. Oh and don't let Jonathan fool you he's going for a Phd :applouse:Quote:
Originally Posted by reefy86
A hammer helps, but...
The epoxy drills easily, no problems there. However, assuming M5 cap screws through nominal 6mm holes in the rails, you have a bit of wiggle room if you get the holes accurately placed. One way to do this is to clamp the rail in place as accurately as possible, then "spot" through the holes with, say, a 5.9mm drill just enough to leave a small mark in the epoxy surface. Then swap to the tapping size drill and pick up the mark to centre the drill in the hole. This is an old toolmakers' trick. However, it's quite difficult to hold the drill vertical when doing this, and if the tapping hole is slightly off then you end up with the cap head slightly off as well once fitted, which makes tweaking rail position more limited. You can do it with care, but I chose to turn up a steel guide bush with a spigot to fit the counter-bore in the rail and a central hole to guide the tapping size drill. One hand to hold the guide in place and the other to do the drilling worked OK for me. Saves a lot of drill-swapping as well. I used a similar guide bush for the tap. It's worth getting a couple (you'll need a spare, just in case) of spiral-point taps which will go straight through without the wind in/back off motion you need with hand taps. Stick one in a cordless drill on slow speed, use a touch of tapping compound, and the tapping is easier than the drilling.
As Neale says a steel guide bush is a useful tool if using profiled linear rail similar to this one I made...
Attachment 15945
I've shown how I did it (I used my pillar drill clamped to the machine bed) here...http://www.mycncuk.com/threads/2148-...-Planes/page40 and there's a video on the next page of my build....
Using a pillar drill would make an enormous difference - it's difficult to get the downward pressure using a handheld drill, then you wobble (did I mention the need for a few spare drill bits?).
Knurling the bush is just showing off. I just threw an odd bit of steel in the lathe. Should have done it before I had already drilled one and a half of the long X rails...
I knurled it because I did that one for someone on here, I even chemically blacked it for good measure [emoji6]Quote:
Originally Posted by Neale
I did consider making a single bush with a hole for the tapping size drill at one end and a hole for the tap at the other end...
But then there's not as much of the bush in contact so the chance of wobble is greater?Quote:
Originally Posted by Neale
cheers guys, im going to look for a decent pillar drill as i want this project to be perfect :) any decent ones to recommend ?
cheers
ash
Hi All,
Sorry to resurrect a four year old thread, but I'm trying to do a post-mortem of why my epoxy pour went so wrong.
I was using West 105 with the 209 extra slow, mixing 3.5 parts by weight 105 to 1 part 209 - in my book thats 350g to 100g.
The air temperature was about 21 degrees when I poured, which the manufacturer states: Pot life at 72°F (22°C): 40 to 50 minutes - we didn't get anything like that. The full description of what happened is in my build thread (here), but short story is we mixed 1.3L into one pot in 6 stages, stirring for a minute at each stage.
We then thought lets leave it for 10mins for the bubbles to rise, but we didn't realise the temperature of the mixture was rapidly increasing. By 8 mins into the wait, the whole thing was burning hot and we started to pour as the plastic container was melting. That kinda ties in with the manufacturers Pot life at 95°F (35°C): 15 to 20 minutes.
How do I get it to wait 72hours? Mine was rock hard within minutes, you guys are still leaving fingerprints after days! Was it just those few minutes waiting that screwed me, or should I mix a small amount, pour, then mix more and pour over?
I've only done this a few times (3 in fact, 1st time was not so good, 2nd and 3rd went OK !) and used exactly that epoxy mix. I think what has happened in your case is if a lot of mixture is altogether in one pot then the heat from the parts of the mix in the middle cannot escape so it heats up. This promotes rapid onset of the curing of the rest of the mixture which releases more heat in a runaway reaction. I'm sure they mention somewhere not to mix large quantities in compact containers.
I think you will get ~72 hours when it is all spread out in your moats, so in my view it needs to be mixed and poured straight away. I didn't see much escaping of bubbles after the stirring when I did it as it is such as dense mix, so I don't think waiting helps (is my limited experience).
I only mixed about half that amount in a relatively wide plastic jug, alternating between 105 and 209 and think I only stirred at the end, slowly to avoid incorporating more bubbles. Then I did what others had suggested (Clive?) - the "2 jugs" method.
The fresh mixed is carefully poured into a second jug, which seems to promote some of the bubbles to be released, possibly because in the thin stream that pours from one jug to the other they are forced to the surface.
This second jug has a ~5mm hole towards the bottom of one side covered with tape and once all the mix has been transferred across you hold the jug over the machine, release the tape, and this will pour out into the moat. Again this seems to prevent too many bubbles getting into the moat.
Leave a small amount in the jug as this will be very aerated.
Here was my second attempt on the X axis:
https://www.youtube.com/watch?v=FDrcpnVUcEE
And using this method on the Y axis:
https://www.youtube.com/watch?v=aw0pM_uV1kw
Know this bit old now but seen as I've probably got the most experience with using this method with more than 20 machines poured ranging from small to 10x5 feel should add my bit.!
Reason you failed was purely because poured to large qty then waited too long. The resin and hardener type wouldn't made any difference, would happened with any type in this instance because of the waiting. I've mixed n poured 1.5ltr without any issues but you cannot hang about after mixing. When spread across the machine the exothermic reaction is much slower so doesn't happen.
To be honest you only need to wait a minute or two then pour, any bubbles you can get as they occur by flashing with blow torch.
Also the hardner type isnt a big deal. The extra slow hardener is good on large machines because gives plenty of time to find it's level n settle. However standard slow hardener works perfectly fine even on 10x5 machine provided the conditions are good.
However in all cases it's good idea not to touch the resin or remove the moats etc for at least a week, personally i leave mine 2 weeks before touching.
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