[peteeng]

Hi Boyadage - What thickness are you going to pour the 105/209 ? Exotherm comes to mind... add a little pigment to the mix so you know when its mixed. Can be some paint if you have it just a few drops to tint. Peter

[boydage]

Oh awesome idea. I have some black pigment I am using for some rubber casting.

I worked out I have 9.6m total of 76mm wide rail. I drew a rail complete with 10mm radius edges. Then a line 5mm above the rail which then had two short vertical lines down to include the point below the radius ie if I wanted it completely flat. Then extruded it measured the volume to be 4.000066L. I'm going to pour the whole 5L that I mix.

I think I will have approx 6mm thickest 2mm thinnest (4mm difference from centre to end of main rail where it's curved)

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[boydage]

So correct that I key the surface up for the epoxy to stick too aye? Was thinking 80grit on the grinder.

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[peteeng]

Hi Boydage- 2mm to 6mm will set level. Its not a process I recommend but its done. Steel is 200GPa stiffness and epoxy is 2.74GPa (from the west data sheet) so its like rubber. I've been using West for over 30 years on different things. One issue is that if the relative humidity is up you will need to preheat the steel with a hot air gun to blow off the surface moisture. I have had west 105 disbond from clean steel due to moisture on its surface at high RHs. Keep us informed. Peter

80G very good Peter

[boydage]

Interesting. Thanks. Hmmm. I might do a bit more research. I was an auto painter in a previous life I have a 2 pack etch primer here the mist type excellent for steel then paint.

So the linear rails are 30mm. Fixings at 150mm spacings.

I will see how it goes and report. Thanks. Boyd

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[peteeng]

Hi Boydage - One thing that seems to help is to brush or use a finger to smear the epoxy onto the surface thinly before you pour it ie like a primer. I can't explain this but tests show that using a finger (gloved please) to smear improves adhesion over just pouring it on. Can't even guess why this works but in one test we went from <100kgf failure to 700kgf using the finger approach Peter

[boydage]

Curious about how best to box in the epoxy? I've seen timber. Foam tape. Am thinking alloy tape bent up.

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[boydage]

Also. And another curiosity. Machine has 8 feet with 3 x M12 grub screws on each foot for feet. Then a M12 dyna bolt to the floor.

It has a curve down the Y gantry rails from the welding underneath. I am going to epoxy it to flat.

Question though. Do I level the machine out best I can and make it solid on the floor? Or? I can actually pull the bend out using the two middle feet with the dyna bolts? Well, with quite a lot of torque on the nuts it moved slightly.

My initial thought is to not do that second option but to leave it solid, bent, leveled with epoxy. Anyone agree or disagree?

Oh. BTW I put a dial indicator on the middle of a Y rail and jumped up and down with my 85kg. Not even a 0.001 movement up/down shown. Pretty happy with that so far. Boyd

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[peteeng]

Hi Boydage- conventional machines design has 3 feet for levelling and secondary feet for stability. This is predicated on the fact that the machine is stiff enough within itself, it just needs levelling. If the machine is connect to the earth then the same applies it is bolted to the earth then levelled. If you try to have it preloaded or prestressed you run the risk of something slowly loosening or settling in over time , hence you will lose the level. Better to make the machine as true as possible then level it, then in future you will know that no changes to the machine are possible. Have you considered self levelling concrete. Much stiffer & cheaper then epoxy. Peter

[boydage]

Hi Peter. Is that a fact? My floor is definitely not flat, it is the result of several pours out of extending the workshop. Infact several feet were not touching the floor hence the grub screws for feet. Hmmm, yeh I think I went for 8 just because its so long and they cost me the steel only. I guess I want this to be nice and solid with good placement.

I agree with you and the initial plan was to just make it level and finish it with the epoxy.

I had a thought go through my head, and at the time had someone in my workshop that doesn't understand workshops. You know, the person who stands there looking around thinking how much of a waste of time it must be hanging around in a place like this with all this unidentifiable stuff in it. And can imagine standing there with him/her in the future, and hearing a small, "tink....... tink.......... then DUNG!" as the middle dynabolts let go and the frame bananas back hahaha

But in all reality across both of the 2850mm rails its actually just under a 3mm banana over the whole 2850mm. I am expecting a maximum 5mm deep pour, 2mm thick on the high spots, think that will be enough to get a good flow. And the sides are actually almost identical. I am in NZ. I could find only 2 shops that sell West 105 with 209. My luck was, I have a mate who purchased the 209 for me on his account out of town. And, how's this, he reckoned he owed me money a while ago, so it cost me $147 for the kit ha. I did start to look around for other products but once I called him there was no stopping the help.

Ok. I will report on second stage! Boyd

[peteeng]

Hi Boydage - which comment is the ? When a machine is set up for final machining if you bolt it to a machine bed in 4 places then machine it then bolt it in a different place the machine will be a different shape. If you bolt it in 3 places, machine it then set it in the same 3 places it will be the same shape. Then the outrigger screws are nipped down. I'm talking about setting up precision machines. HAAS has a good manual on how to set up machines if you have a look on their site. Some machine builders don't "fix" to the ground some do. HAAS say the machine is better if fixed to the ground.

You could establish two corner screws on one side and one of the middle screws on the other side as your master feet. Always use those for levelling, Especially if you move the machine. In this way the "gravity or natural" shape of the machine is always the same .

My approach would be to use a foundation plate on top of the frame that is milled or ground flat and bed the foundation to the frame. This way the rails are on metal not on epoxy. The foundation plate could be adjusted with grub screws then tacked or screwed lightly to the frame. Then the plate would be bedded in epoxy. But a bit late to think that through. Lots of people use epoxy to level their rail bed and it works for them... You are discovering all the fun issues that others have discovered going down the steel welded path ....Peter

[boydage]

Apologies that was me joking the humor lost in type.

My aim, is to build a better frame than the timber original frame I have been using to cut alloy to 65% standard. This will be great.

What I have done is made it level. Preloaded all the grub screws and tightened the dyna bolts. This way it can be moved one day and not spring out of shape. Yes correct it's a little late to do much else, and tbh there are not many machining options in my location. I'm going to pour the epoxy tomorrow end of day using the techniques learned here.

I do have a few 2mm pilot holes and am wondering if the epoxy will flow through them or membrane over the top? Using West 105 with 209.

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[routalot]

Epoxy will flow through those holes if they are left open.A small square of flashbreaker tape or a tiny wooden plug will prevent it.Good luck with the epoxy pour,don't mix it until you are sure it will stay where its needed and not make it's way to the floor.

[peteeng]

Boydage - When pouring epoxy down a hole the hole needs to be big enough to allow air to flow out one side and the epoxy down the other side. 2mm is too small, as soon as it wets all round it won't flow much. Unless you can create some negative pressure in the cavity being filled eg connect one of the 2mm holes to a vacuum cleaner or vac pump. 6mm is minimum I think and you will have to feed very slow. A big syringe maybe the go then you can put the needle down the hole and push it in. I use large veterinary needles not human size from pharmacies way too small. But you have a lot of resin to fill... Peter

found an image of me pouring a plaque. That's about the size of pour you will need to fall through a 2mm hole. Its a plastic cup cut in half so when squeezed it makes a small lip. This resin is also much thinner then 105 as its an infusion resin so its stream is thinner then 105 will be.... try a test hole somewhere before you commit... good luck

[pippin88]

I did epoxy levelling with West 209.

Did not work well for me. Not sure I would do it again. I had areas about 2mm thick.

I found some reference later that it needs to be like 6mm thick to self level properly.

Epoxy is soft. There is an impression from my rails / mounting blocks etc in the epoxy.

You must seal you dam or your expensive epoxy will all be on the floor. You can use a small amount of quick setting epoxy in the seams.

For wood routing, it probably works well enough. Just don't measure the results with a master reference and DTI. When I did this (trying to square gantry perfectly), I found it be wavy / out by up to 0.3mm over about 500mm (from memory).

[peteeng]

Hi Boydage - reread your post and routalot is correct that the epoxy will flow thru 2mm holes easily. If you mean by pilot that its a hole somewhere and not something that you want to fill through like I imagined. So they will have to be taped close or use a putty to close out. Its worthwhile painting the surfaces with epoxy first to close out any small holes or weep points. When the coat is tacky then do your cast..... good luck show us how it goes...Peter

[boydage]

Ok pleased I posted here I am going to go around my moat and double check integrity. I will be putting a very small bead of window installation sealant down into the radius of the box section where it meets the boxing. When that is dry this evening I will pour.

Also not sure I mentioned I was told to mix with large flat paddle in a very large container with large surface area to allow the heat to escape. By doing this I will avoid bubbles and it, well, heating up which we don't want. So will source one today whilst the sealer is going off.

It appears this epoxy will run quite well. I did read about putting a layer on prior, in a first mix, and rubbing it down with gloves to improve adhesion. I will do this in two mixes yes and the next one goes on over the slightly tacky first?

The 2mm holes I will plug with battleship pins, or cloves or similar. Anyone still play that game haha?

Ok I have been undecided but will pour a full 5.33L total which is very close to what I worked out to make a 5.5mm thick surface should the rails be flat. That will mean the highest point will have approx. 2.5mm the lowest 6.5mm. And hey, if I need to shim with a nice flat shim I will. I bought a meter of a lot of sizes.

Using SBR30 rails. I am considering adding in some mounting holes, currently the SBR30 has mounting holes at 200mm centers including the cap screw underneath into the bar on the same plane. Is there advantage to making them 100mm? Although I am not going to add the one to the bar its way to hard. So may be pointless. Dunno. I do like connections.

And also curious about the epoxy that was so soft the rails left an impression? Like, its not that hard but I would be surprised if it compresses to that kind of problem? I read it has a 12000PSI compression way more than a M6 bolt will give. Perhaps something was not fully correct in that pour or the epoxy had expired? Gee, that happens to me its coming off. Ok will post a pic later. Happy Sunday

[peteeng]

Hi Boydage - Running your Q's:
1)std paint paddle is fine, I use a steel ruler and clean it everytime. More about the speed of mix then the size. eg power mixing entrails air
2) the std hole space is fine for the round rails
3) sorry 12ksi is 82MPa. If you look at the compression test this is the stress required to deform the material a certain amount. It maybe 5% or 1% depends on the test. Plastics and other materials do not fail under compression load they just deform and spread out. That's what happens with the epoxy under the rails. Epoxy does not expire. Its good for several years if kept in airtight container, I've used epoxy that's 10 years old and its fine. Unless its solvated then the solvent can evaporate and it will be thicker then expected but the active components still work. Don't pull down the rails hard too early let it cure properly for best result. Keep at it Peter

also plastics are viscoelastic and creep and relax. Over time the material will flow and deform and will not recover under static strain conditions.... sorry about the negatives but people do it...

[boydage]

Hi. Thanks. And thanks for the conversion I was considering the advantages of the epoxy they used to install/level a Fluro machine in a hospital which was 90mpa.

Just so I am clear. The advice, is mix say, 500ml. And smear/wipe that on the surfaces. And then, when it's tacky, to pour the remaining? This will improve adhesive properties to the steel?

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[peteeng]

Hi Boy - Its for two reasons. 1) let the epoxy get quite tacky. This fills/seals the gaps and stops the pour going thru the small cracks. Leave it till its quite tacky as it can reflow if it gets warm from the big pour. Plus you can have a look around and see if there are any weeps to deal with 2) It adheres to the material better if mechanically rubbed to the surface vs flowed onto the surface. Good luck Peter

info on compressive test

Compressive Strength Testing of Plastics