Advice on Mammoth CNC Router Build - Steel Framed - 2440mm x 1220mm cutting area!

[EddyCurrent]

I don’t know if I’ve misunderstood Jazz here or you with regards to shimming...

Surly enough accuracy can be achieved when cutting and then wielding the frame that any small differences would be "levelled" out from doing an epoxy bed for the rails to then sit on?

To confirm, what it sounds like your suggesting is, having the ability to “shim” the 3m lengths, along their lengths.

.Me

That's the method I'm also using and I found that after welding, one corner of the frame was 3mm out of level with the other. This might be regarded as too much depth for epoxy treatment alone. I don't know for sure ? but at least I can shim the rails to as near level as possible then use epoxy from there.

[Clive S]

That's the method I'm also using and I found that after welding, one corner of the frame was 3mm out of level with the other. This might be regarded as too much depth for epoxy treatment alone. I don't know for sure ? but at least I can shim the rails to as near level as possible then use epoxy from there.

Eddy You might have seen this before there is no problem with the thickness of the epoxy Jonathan and I have used it I think Dean uses some sort of epoxy putty which is stiffer, he has explained that on other threads.

I poured this to about 5mm deep it is very slow setting 10 - 20 hours and don't touch it for 48 hours. Wests system
..Clive

[Lee Roberts]

That's the method I'm also using and I found that after welding, one corner of the frame was 3mm out of level with the other. This might be regarded as too much depth for epoxy treatment alone. I don't know for sure ? but at least I can shim the rails to as near level as possible then use epoxy from there.

Thanks Eddy, any idea why this happened or?

Eddy You might have seen this before there is no problem with the thickness of the epoxy Jonathan and I have used it I think Dean uses some sort of epoxy putty which is stiffer, he has explained that on other threads.

I poured this to about 5mm deep it is very slow setting 10 - 20 hours and don't touch it for 48 hours. Wests system
..Clive

Hi Clive, in your picture to make your epoxy "gutters" you look to have used MDF, i dont know if you've seen Jonathan's recent machine but he made his using aluminum and then left those in place once the machine was ready. My question is, what are the edges like on the epoxy once it "sets", i.e dose it need protecting from damage and so on to keep it together.

Did you do anything to yours after the machine was ready to be used to keep it safe?

I tend to agree - there becomes a point when an extra couple of mm of epoxy doesn't cost much compared to the added material/time required to get the frame more accurate. The epoxy is pretty strong/hard and the damping properties may be useful, so I wouldn't be too concerned about minimizing the thickness, within reason. If you look in my build log the epoxy is quite thick, but don't treat that build log as gospel - there's plenty of room for improvement.

Thanks JB, I didnt see your post untill i posted mine.

.Me

[Clive S]

Hi Clive, in your picture to make your epoxy "gutters" you look to have used MDF, i dont know if you've seen Jonathan's recent machine but he made his using aluminum and then left those in place once the machine was ready. My question is, what are the edges like on the epoxy once it "sets", i.e dose it need protecting from damage and so on to keep it together.

Did you do anything to yours after the machine was ready to be used to keep it safe?

It is 10mm MDF the box section is 60x60 the MDF is placed right on the edge (just on the round part of the box) and then a very thin bead of silicone was run around the inside of the moat to stop any leaks. I also rubbed a little oil on my finger and ran that around to stop the epoxy sticking to the MDF.

The epoxy is like water and runs around ok. When it was cured the MDF was removed (the epoxy creaps up the inside of the MDF a little) Then I used a scraper and a flat file to get rid of the edges that were raised, it is easy to see when you are scraping it because it will start marking the centre.

The rails were then screwed right through the epoxy into the steel. Job done. The epoxy can be chamfered off at the edges as it can be very sharp like glass. ..Clive

[Lee Roberts]

It is 10mm MDF the box section is 60x60 the MDF is placed right on the edge (just on the round part of the box) and then a very thin bead of silicone was run around the inside of the moat to stop any leaks. I also rubbed a little oil on my finger and ran that around to stop the epoxy sticking to the MDF.

The epoxy is like water and runs around ok. When it was cured the MDF was removed (the epoxy creaps up the inside of the MDF a little) Then I used a scraper and a flat file to get rid of the edges that were raised, it is easy to see when you are scraping it because it will start marking the centre.

The rails were then screwed right through the epoxy into the steel. Job done. The epoxy can be chamfered off at the edges as it can be very sharp like glass. ..Clive

Thanks Clive, I liked the tip on silicone, will add that to the mental archive for when the time comes. Good idea on the chamfering, i was thinking about what i could use to protect it once done but it sounds like its quite durable.

Clive, where is your build log?

.Me

[EddyCurrent]

That's the method I'm also using and I found that after welding, one corner of the frame was 3mm out of level with the other.

Thanks Eddy, any idea why this happened or?

Because I assumed my garage floor was level and I just built it from that datum.