[gt40]

gt40 are you sure that base and column are big enough? 482mm x 940mm x 203mm at 2,500kgm^-3 is only 230kg (507lb). I think you changed the Y travel to 15"??? This is better than the original 20" of Y travel, but a industrial machine with ~15" of Y travel will weigh 2,000kg+ (4,400lbs+) and still be considered light weight...

You mention your RF45 deflecting too much while cutting steel but how will this machine differ? Your build is obviously early stages but I can't see it being any more rigid than the RF45, and a 10hp spindle will only make matters worse... Getting 20" of travel from 780mm rails leaves only ~250mm carriage spacing (end to end) to support the table / head with.

Am I right in thinking you're expecting the steel plates to remain perfectly flat and parallel even when cast? Or are you going to scrape the plates flat or something once cast?

Sorry if I sound really negative, it seems to me that you haven't planned this out sufficiently. By the time you've finished you'll probably have spent enough to have bought a working used machine, which will be rigid and precise enough to do the work you want without all of the hassle of building the damn thing.

I hope this helps,
Fenza

I am only 4 years into cnc and it is at the serious hobby stage. I want to make some 3d stuff in limited quantities in steel and I want it to be more accurate than my RF45 clone- these things are the basis for doing this build. In a perfect world, I would have Brother Speedio but as the wife won't sign off on that just yet, this is the current upgrade.

As far as the design, I am trying to keep each major components at 700 lbs / 300 kg. It will also be bolted on a much larger subframe that will add considerably to the mass I expect the full mill with the subframe( still finalizing the design) will be around 2500 lbs/1130 kg. I got all my rails, thk and nsk 32mm ballscrews and basic materials for 2k so far. Add my time and spindle + electronics pneumatic draw bar and I hope to be well under 10k. I think if I can achieve this price point with the components I am using it should be a major step up from my current mill and hard to beat in terms of cutting ability, accuracy compared other mills in this price.

I am still tweaking the vertical column. 11x12x36 is the current dimensions and re enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.

Most important, when I finish, I will know the machine inside and out and be able to maintain and fix it if need be. Modern VMC's can be very complex and expensive to fix and there is the learning curve. I also would rather start with new stuff than learning fix someone elses mess.

To your comparison with an RF45, I am not sure how familiar you are with these machines. The column is 7x9 tapered hollow cast Iron, as is the base. I can pick up and move the column, the base or the table by myself. The whole machine is only around 800 lbs/350 kg without the motor and stand. Going from a RF45 to this build will allow me to replace dovetails with THK linear rails, 3 times the mass and the room to fit proper sized ballscrews and servos.

I am still tweaking the vertical column. 11x12x36 is the current dimensions and re-enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.

You brought up an interesting point on the steel rails. I tested a 1/2"thick piece a foot long cast at the bottom of a box mold placed on a granite surface table. It was dimensionally unchanged. The ground steel will be through bolted to the mold and cast in a horizontal position with the epoxy granite on top in the same manner as my test. We will see for the bigger piece. I guess I will scrape or grout as needed.

For my part, the biggest thing I am trying to work out is mixing 3 - 4 cubic feet of epoxy granite per pour for each section. I have planned for a total of 25 gallons.

Thanks for the challenging questions!

[wizard]

I am only 4 years into cnc and it is at the serious hobby stage. I want to make some 3d stuff in limited quantities in steel and I want it to be more accurate than my RF45 clone- these things are the basis for doing this build. In a perfect world, I would have Brother Speedio but as the wife won't sign off on that just yet, this is the current upgrade.

I'm not sure this machine will get you there. I think you are missing some important points. The number one point is that mass isn't everything. The first consideration is that you need securely mounted rails and frankly I'd be worried about the machine tearing out your rail mounting plates.

As far as the design, I am trying to keep each major components at 700 lbs / 300 kg. It will also be bolted on a much larger subframe that will add considerably to the mass I expect the full mill with the subframe( still finalizing the design) will be around 2500 lbs/1130 kg. I got all my rails, thk and nsk 32mm ballscrews and basic materials for 2k so far. Add my time and spindle + electronics pneumatic draw bar and I hope to be well under 10k. I think if I can achieve this price point with the components I am using it should be a major step up from my current mill and hard to beat in terms of cutting ability, accuracy compared other mills in this price.

I am still tweaking the vertical column. 11x12x36 is the current dimensions and re enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.

why not place the square column on the onside and machine it to mount the linear rails.

Most important, when I finish, I will know the machine inside and out and be able to maintain and fix it if need be. Modern VMC's can be very complex and expensive to fix and there is the learning curve. I also would rather start with new stuff than learning fix someone elses mess.

To your comparison with an RF45, I am not sure how familiar you are with these machines. The column is 7x9 tapered hollow cast Iron, as is the base. I can pick up and move the column, the base or the table by myself. The whole machine is only around 800 lbs/350 kg without the motor and stand. Going from a RF45 to this build will allow me to replace dovetails with THK linear rails, 3 times the mass and the room to fit proper sized ballscrews and servos.

Again mass isn't everything. To function better the machine needs to be structurally stronger. In this regard I'm not getting good vibes about this machine.

I am still tweaking the vertical column. 11x12x36 is the current dimensions and re-enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.

You brought up an interesting point on the steel rails. I tested a 1/2"thick piece a foot long cast at the bottom of a box mold placed on a granite surface table. It was dimensionally unchanged. The ground steel will be through bolted to the mold and cast in a horizontal position with the epoxy granite on top in the same manner as my test. We will see for the bigger piece. I guess I will scrape or grout as needed.

For my part, the biggest thing I am trying to work out is mixing 3 - 4 cubic feet of epoxy granite per pour for each section. I have planned for a total of 25 gallons.

Thanks for the challenging questions!

Get a cement mixer!

[gt40]

I'm not sure this machine will get you there. I think you are missing some important points. The number one point is that mass isn't everything. The first consideration is that you need securely mounted rails and frankly I'd be worried about the machine tearing out your rail mounting plates.

why not place the square column on the onside and machine it to mount the linear rails.

Again mass isn't everything. To function better the machine needs to be structurally stronger. In this regard I'm not getting good vibes about this machine.


Get a cement mixer!

I am really not sure where you are coming from on some of your points. The base is stable massive and extremely strong. I reinforced the structure with rebar, 6" 3/8" bolts + the a2 tool steel is additionally embedded. I also added 2 steel pipes for lifting:

Attachment 279678

The a2 steel ground steel cast fine in alignment and the linear rails are through bolted to the steel via coupling nuts and 5" x 3/8" bolts embedded into the reinforced epoxy matrix every 80mm. You obviously don't understand the build if you are thinking the rails are going to be pulled out when they are cast in place this way.

The whole base is a 2ft by 4ft x 10" rock that is reinforced with steel throughout and is monolithic. I struck it with a sledge hammer like I did and it just bounced off. I look forward to continuing to the build after my move but I am quite satisfied that the base is meeting my design goals.

[Voyager77]

I'm not sure this machine will get you there. I think you are missing some important points....

Have a look at your attitude 'wizard'. Mark is sharing his build with us, posting photos and inspiring others. Your post is not helping the project in any way. Perhaps you can link to some of your own, successful projects rather than criticise others?

Best regards
Frank