[G59]

The problem with showing a build in progress here, is you will be criticized by a thousand arm chair engineers. This can make you second guess everything to the point of constant changes being made and soon when you run out of patience or money, you end up with nothing.
It's your build. You know the basics of what is needed, so just go with your plan.
A few month back, I too had a vision and when I posted my drawings or model, most criticized it and yes I made many changes to the original plan. In retrospect, all they did was stall my build. I learned. Being an engineer by profession, I stopped updating my models and went solely on my knowledge and experience. Today I can say my build is going well, and when it is complete, I will post how it was done.
I think you are headed in the right direction.
To prove what I mean, how many here know the real reason for having the column bolted down on two footings instead of just one square column with a flange bolted all around.

I think you're doing great.

[gt40]

The problem with showing a build in progreas here, is you will be criticized by a thousand arm chair engineers. This can make you second guess everything to the point of constant changes being made and soon when you run out of patience, you end up withnothing

No worries- I am appreciating other perspectives and it makes my design better. The new base is an improvement and supports the x axis better + stronger and 30% more mass. I will grind/grout the rails as necessary to get them perfect. I got the steel cheap on ebay and it adds significantly to strength. I think thick steel bar cast flat should stay such but it should be an interesting observation in any case and I am hopefully starting from a pretty decent place compared to some regular hot rolled steel. I had to order extra epoxy however :P

[nateman_doo]

One of the tags in this thread is tormach. Do you plan to use a tormach head?

[gt40]

One of the tags in this thread is tormach. Do you plan to use a tormach head?

I am not using a Tormach head. No idea how this tag got in here :P I am looking at 5- 7.5 hp 10k spindles

[RotarySMP]

Cool build. are you going to use a commercial aggregate, or make up your own?

[gt40]

Cool build. are you going to use a commercial aggregate, or make up your own?

Thanks for the interest. I have 12 gallons of epoxy so I guess I will be rolling my own. I would be open to a cost effective commercial mix but I wasn't aware of any

[G59]

12 gallons?????
what is the epoxy to aggregate ratio???
that seems like alot since the epoxy is supposed to be the binder only, and not the actual structur. Something is wrong here.

[Voyager77]

Hi Mark,

Epuself is the only premix option that I am aware of

Do-it-yourself Materials:

Their main business is manufacture of polymer concrete machine beds for third party vendors. If you haven't seen the videos yet, you might find some interesting details...

https://www.youtube.com/user/EPUCRET?spfreload=10

To prove what I mean, how many here know the real reason for having the column bolted down on two footings instead of just one square column with a flange bolted all around.

I would be interested to hear the benefits of the split column design?

[G59]

The biggest benefit of a split column design, is the reduction of vibrations being transferred from the column, to the base. If we'll implemented, it can even cancel them out. It however has its own disadvantages.
The biggest one is it adds to the complexity of your molds for both the column and the base. It is also less rigid then an all sides flanged column of the same size. However if properly engineered, it can achieve the same performance.
Vibration travelling through the column are split in two thereby reducing there amplitude in half which are then, disippated through the base as two waves and when they collide with each other towards the centre, most will have cancelled each other out.
make any sense to you?

[gt40]

12 gallons?????
what is the epoxy to aggregate ratio???
that seems like alot since the epoxy is supposed to be the binder only, and not the actual structur. Something is wrong here.

Well, the base alone is going to 650 lbs/295 kg. 12% of that is 78 lbs/35.3kg worth of epoxy assuming a gallon is about 9 lb/4kgs.

Maybe I can get to 8-10% epoxy to aggregate but figure some loss from mixing it and transferring it between containers. I have worked with carbon and fiberglass composites and figure it is good to have a bit extra.

Heh, maybe I am too tired from my day job as a portfolio manager- It is possible to fail math in the afternoon after getting up at 430am every day for years...

Voyager- thanks for sharing on the EPUSELF. Any idea on the pricing and if it is available in the states?

On a final note, I had a detailed conversation with DMM Tech about servos. I have had great success using their 750watt servos on the RF45 clone mill and 400 watt on the 13x40 jet lathe. Going with 1.3kw all around with the 16 bit encoders and new drives. They have provided me really good support on both builds and the price is right + I have 3 years of hard use on the mill with no issues. This thing should fly with the jumbo ballscrews and servos...

[RotarySMP]

In Europe I know of Silimix 282, and Sikadur as Fuller curve pre graded aggregates. Sikadur is a only sold with it's epoxy, silimix as dry aggregate.

For me Sikadur is too expensive, and silimix would be okay, but the shipping from Germany makes it prohibitive. I am currently experimenting with a self graded aggregate (I posted the recipe in the big E/G thread last week). For the first test piece I used 10% epoxy. Next test will have 8%.

Any idea what that EPUSELF costs?

[rybov]

In Europe I know of Silimix 282, and Sikadur as Fuller curve pre graded aggregates. Sikadur is a only sold with it's epoxy, silimix as dry aggregate.

For me Sikadur is too expensive, and silimix would be okay, but the shipping from Germany makes it prohibitive. I am currently experimenting with a self graded aggregate (I posted the recipe in the big E/G thread last week). For the first test piece I used 10% epoxy. Next test will have 8%.

Any idea what that EPUSELF costs?

If I remenber correct I think it was EURo 2.5 / kg delivered to Denmark. EPUSELF is good product and very easy to use. I have only had good results with it. And also the help and support from EPUCRET is very good.

Jacob

[arvidj]

Anyone have any thoughts about a USA version of the EPUSELF concept?

[Voyager77]

I believe EPUSELF is targeting small scale production without dedicated tools such as vibration tables or elaborate mixers. I have heard their solution has a higher epoxy percentage to make the casting process easier. Sorry, don't know the cost or availability in the US. However Rampf is present in the American market and a quick phone call could get you answers.

RAMPF Group, Inc.
49037 Wixom Tech Drive Wixom, Mi 48393, USA
T: +1 (248) 295 0223
F: +1 (248) 295 0224
RAMPF USA | Reactive resins, dispensing equipment, tooling products:

[rybov]

Voyager77, you are right. EPUSELF comes in pre-measured bins with the aggregates and the resin. The bin can be used to mix the polymer concrete in by just stirring with a mixer. The epoxy percentage is higher than in their professional services concretes to make it easier to mix and increase flowability. This makes the EPUSELF a little bit weaker than the professional concretes, but not by much.

I am not associated with Rampf. Just a happy customer.

Best
Jacob

[arvidj]

Voyager77 and Jacob, thanks very much for the information. I've sent an email to RAMPF in the USA and will let everyone know what I get for a response..

[gt40]

Update:

I have the mold for the base almost finished and the ground steel bases for the linear rails aligned and bolted to the mold. The two 1/2" thick 3" wide bars also have the benefit of supporting and keeping the mold really flat. Pic of the mold with the ground steel bars bolted and aligned:




My epoxy just arrived and I should have the "flour" portion of the aggregate mix tomorrow.

FYI, the "flour" is from a pottery supply house and is Custer Feldspar, so names because it is a type of mineral mined in Custer, SD, is made up of silica and alumina combined with sodium and potassium oxides, It is finer than their 320 grit stuff they had and the price was right at 50 bucks shipped for 55lbs.

I have 3 size sands, decomposed granite to pea sized gravel also.

I plan on casting next week now that I have everything together.



Thanks for looking

[gt40]

I picked up a 1000 lbs of aggregates and sand and rinsed about 300lbs of the larger sizes. I was able source everything local to avoid shipping costs but the "flour" portion made up of powdered quartz and alumina- I got that online from the big ceramic store 50lbs for 50 bucks including shipping. FYI, it really does feel and look like fine flour. Everything else came from Home Depot and the local West LA Building Supply store.

On top of that, the epoxy came:

Attachment 272632


Supplies:

Decomposed granite, 60 grit sand, small pebbles and a giant 90 gallon mixing tray:

Attachment 272630


Unloaded:

Each sand bag is 100 lbs and the rest are 50 or 75lbs + more in the garage

Attachment 272634

I am easily amused but the mixing tub really is awesome- you can mix the whole batch in one shot.

Attachment 272636

Here are the different aggregates:


Attachment 272638

To promote adhesion, you need to wash them and let them dry properly. The decomposed granite was really dirty:


Attachment 272640

30 and 60 grit sand also- I didn't have to wash that because you can buy graded washed and kiln dried fairly cheap in 100 lb bags.


Here is a close of the mineral "flour"

Attachment 272642

Well, my arms are sore but I hope to be able to pour the mold this weekend if I can get the rest of the aggregate washed and dried...

[RotarySMP]

Cool, this is about the same set of sizes as I have except you have one size larger pebbles. What recipe are you using to approach the Fuller curve? I am using Thomas Zietz's XLS with a 0.4 grading increment, plus 8% epoxy, and have about 50GPa young's modulus (7.c x10^6 psi)
Mark

[arvidj]

... but the "flour" portion made up of powdered quartz and alumina- I got that online from the big ceramic store 50lbs for 50 bucks including shipping.

Mark,

Was this the "flour" you used ... Laguna Silica, 200 Mesh in Bulk ...

I am in search of "flour" locally and need to have something as an example as "quartz flour" is getting the deer-in-the-headlights look when I ask about it.

Thanks,
Arvid