[veteq]

You are right Tom, sorry, my Portugese isn`t like it used to be.....
LOL.

Kind regards,

Roy.

[PedroS]

Hi

I'm from Portugal , would you like me to help you with that portuguese document?

I'm not in the Epoxy / Granite area , but I could help you with some translation

Regards

Pedro

[Brenck]

Hi guys,

I read the portuguese doccument, I can say for you all, they made tests without any kind of vibration. The mix that they got the best results was using a agregate mix of particles of granite powder ( no specification on what kind of granite ) it was a mix of particles from 0,106mm and smaller. They used 20% epoxy on weight ( Used an A and B epoxy that are 70% and 30% respectively ).

Their tests where made using a pvc pipe of 1'' inner space, some of them where longer on lenght than others and that changed the test result as well. They let all the experiments cure for 7 days before testing.

What I can take from this document is that if you are going to make E/G at home and dont have any kind of vibrating table, or crazy industrial device to compact more the mix 20% on weight is the way to go... On the document they realize that the mixes with less epoxy where not possible to achieve better resistance due to the fact that they did not use industrial methods of casting EG

If anyone needs more info about that document just feel free to ask and I can read and translate whatever you need.

[lgalla]

Hey Daedalus,

Had just a quick read, but it looks like Zanite uses 8 - 9 % epoxy by weight.
Thats a lot and different then all the studies overhere.

If so, it will make the proces a lot easier.

Happy Year to everybody.

Roy

Walter and I started the thread to help design accurate machines for the hobbyist without the need for welding using E/G to damp and E/P for precision pourable surfaces.The thread is too long based on packing density and no users outher than Bob Warefield.Thanks Bob.
The biggest mistake I see is the confusion on % age.This is important as 9% by volume is much different than 9%by weight.It appears high % of epoxy is ok now
Which is stronger or has better damping?One cu/ft Zanite at 145Lbs or one cu/ft of cast iron at 450 lbs?The Zanite should win as it would be 3 times thicker than the E/G.This is missing from the equation.
I still say for the home users,E/G is excellent to fill mill colums and the webs underside of cheezy iron X.Y mill tables.
BTW a note of interest...The Hubble telescope mirror grinding machine has been throwen in the garbage.500 tons of granite
Larry

[brunog]

Hi guys,

I read the portuguese doccument, I can say for you all, they made tests without any kind of vibration. The mix that they got the best results was using a agregate mix of particles of granite powder ( no specification on what kind of granite ) it was a mix of particles from 0,106mm and smaller. They used 20% epoxy on weight ( Used an A and B epoxy that are 70% and 30% respectively ).

Let me put the amount of epoxy in perspective:

Because epoxy is half the density of the rest of the mix, this means 20% epoxy by weight equals 40% by volume. (chair)

These guys weren't making EG but EEG(Epoxy Encapsulated Granite).

IMHO the "ideal" epoxy level in EG must be enough to fill the gaps and bond the aggregate together. That represents between 8 and 20% by volume or between 4 and 10% by weight.

Larry,
I believe that the "Zanite" or mold volumes are greater than they would be in cast iron and vice-versa. however you must keep in mind is that you can embed your electrical conduits, vacuum and plumbing directly and some reinforcements in the mold. With carefull planning can get an overall footprint that are both equivalent in size.

Best regards

Bruno

[dfro]

Hey guys,

I am using e/g in a diy cnc lathe build. Here is a link to my blog on it:

http://www.cnczone.com/forums/showth...279#post722279

I have finally got around to posting some pics of my latest table vibrator that runs on compressed air. I used it as an opportunity to practice my e/g casting technique. I also posted pics of an unsuccessful table vibrator I made, which used a wood router, a router speed control, an eccentric weight, and plywood. The bearings got really hot and caused the wood to start smoking.

Here is a picture of the latest compressed air vibrator. There are more pics on the blog:



Thanks,
Dave

[dfro]

Here is a picture of my e/g headstock:



More pics at my blog:

http://www.cnczone.com/forums/showth...899#post722899

Thanks,
Dave

[AFAIK]

Hello all.

I have been following this thread for a long time and have decided that I want to make a mill out of E/G. I've come up with a rough design for how I want it, but I don't really know if this design is good enough for E/G.

I want to get the design done first before I start building the equipment needed like the vibrating table etc, although I already have the vacuum pumps coming. Mainly because I'm on a pretty tight budget (if the estimated price of the machine goes too far over it, then I cant do anything on it for 4 or so months)

I plan to cast it as 4 parts; the base, the two supports and the beam going across. If there is some money left over I want to cast 3 long rectangular legs, but if not, then I will probably sit it on the floor.

I'm not exactly an expert on any of this though, so I hope I haven't underestimated this too much or made a really bad design.

Anyway, here are the pictures. Sorry if they aren't very good, I have never used any form of CAD before today.

[greybeard]

Hi AFAIK, and welcome.
That looks pretty massive, in the best possible way.
Not being an engineer I can't offer comments on the structural design, but being on a limited budget myself, my immediate thought on the "any left over money... cast legs" was to suggest that if the legs are only to support the m/c at a higher level, why not use concrete posts ?
Most towns have builder's merchants with quite an array of slabs and posts so you could probably find a suitable combination.
That way you wouldn't have to buy a concrete mixer, like I have
Regards
John

[ckelloug]

AFAIK,

You look very ambitious! Good job on the drawing. So, how are you mounting your Z axis?

Regards all,
Cameron

[AFAIK]

Hey again.

Greybeard,
Thanks for that idea regarding the concrete post and slabs, had a look around and it will cost me around £50-£100 for all three (price difference is due to me not deciding on the thickness yet). Which in comparison to the aggregates, molds and the epoxy resin etc will save me some considerable money. Although I could save even more and just put it on the floor, but would have to put up with a bad back then.

Ckelloug,

http://img4.imageshack.us/g/cncimprovement2.png/

The z-axis is the gantry, there will be two ball screws each side that will go through to the top of the cross-beam and two stepper motors will be attached to them and mounted to the beam. My original plan was too have one in the middle of the gantry and have the ball nut fixed in place so it doesn't move but I'm not sure how long that would last until it got bent by someone being careless.
The x-axis will be a moving table, the table will be a granite surface plate that is 900mm*600mm*100mm, only problem with that, is it weighs 200kg and cost £230. And the y-axis will be attached to the gantry.

Edit: I forgot to mention, that I have altered the length a little to take into account the Ball screws and the rails

[dfro]

AFAIK,
Excellent drawing for your first day with CAD software!
Concrete filled cinder blocks are a great way, in my opinion, to create a massive, stable machine tool base for very little money.

Check out my 'DIY benchtop lathe project':

http://www.cnczone.com/forums/showth...t=42308&page=5

There are some pictures of a base I am building for my lathe out of cinder block, concrete, and rebar. More pictures are on the way.

Dave

[greybeard]

......and just put it on the floor, but would have to put up with a bad back then.......

....and dogs, children and footballs.

John

[RotarySMP]

Have you modelled your gantry with table and Z Axis installed? To mee it looks too symetrical. The Spindle will hang off a fair way on one side, and the center of the spindle should be at the center of the X and Y travel.

[oxford]

I saw this company's name in some of the threads so I wrote them an email basically asking them what was their best epoxy for putting an epoxy aggregate machine base together with.

No response.

Anyone else have any better luck with them?

Thanks

[Steven.ji]

Here is a picture of my e/g headstock:



More pics at my blog:

http://www.cnczone.com/forums/showth...899#post722899

Thanks,
Dave

Dear Dfro

In polymer concrete, the specific heat is very high, and coefficient of heat conduction is very low. That mean it's not easy to conduct heat to outside, then temperature of headstock will increase quickly, which will result precision lost.

How do you deal with this problem above?


Regards

Steven

[AFAIK]

Hey rotary, thanks for that comment, I think I have fixed it now.

http://img714.imageshack.us/g/cncv3c.png/

I have had to make it a bit smaller due to not having anywhere to put it without crushing the floor, which is annoying. The reason for the two external rails and plate is so I can attach the stepper on to the end of the Ball screw as there isn't enough space in the inside. I was planning to use a pulley but I don't know how much backlash they will have.

BTW, is it OK that I post it in this thread? Or would it be better to make my own?

[brunog]

I saw this company's name in some of the threads so I wrote them an email basically asking them what was their best epoxy for putting an epoxy aggregate machine base together with.

No response.

Anyone else have any better luck with them?

Thanks

Oxford,
Seems to me that Precision Epoxy is not a resin manufacturer but more of an epoxy resin user/applicator/contrator type business.

Good luck

Bruno

[RotarySMP]

I think you would be better off making your own thread for this specific build. It will likely disappear into obscurity on his monster thread.

HTD (the rounded tooth form) toothed belts and pulleys are supposed to be back lash free.

Have you a plan for how you are going to get rails on two sides of two separate monoliths parallel and aligned? Four vertical surfaces that need to be parallel and aligned, but can not be cheaply ground after the uprights are mounted to the base does not seem like a practical solution.

If you are planning to use the common E/G method of casting steel mounting rails into the E/G, and then having precision interface surfaces for the Linear bearings ground after it cures, you would seem to be making it very differcult for yourself.

Remember the engineering adage "anyone can design complicated, it takes genius to design simple"!

If you put the Y axis onto the gantry cross beam, with both it's rails on one face, and then mount Z off Y, you will have a much simpler ($$$$) job getting precise alignment.

[RotarySMP]

I think you would be better off making your own thread for this specific build. It will likely disappear into obscurity on his monster thread.

HTD (the rounded tooth form) toothed belts and pulleys are supposed to be back lash free.

Have you a plan for how you are going to get rails on two sides of two separate monoliths parallel and aligned? Four vertical surfaces that need to be parallel and aligned, but can not be cheaply ground after the uprights are mounted to the base does not seem like a practical solution.

If you are planning to use the common E/G method of casting steel mounting rails into the E/G, and then having precision interface surfaces for the Linear bearings ground after it cures, you would seem to be making it very differcult for yourself.

Remember the engineering adage "anyone can design complicated, it takes genius to design simple"!

If you put the Y axis onto the gantry cross beam, with both it's rails on one face, and then mount Z off Y, you will have a much simpler ($$$$) job getting precise alignment.