Stell frame cnc 1500X1000. Adjustable table your opinion please

[ba99297]

First of all thanks everybody for the participation to the thread.
Next i would like to introduce some of my conclusions and ask some things about all these that i have already read

1. I beam will not be used
2. For the rails support beams I am between these profiles
80X80 4 mm
80X80 5 mm
100X100 4 mm
100X100 5 mm
and for the table structure
80X80 4 mm or
80X80 5 mm
i want your advice

Jazzcnc wrote
Now regards the table Bed and getting it parallel to the cutter then don't worry this is not a problem.? Because every time you move the bed or in Fixed bed case Add the raiser block you MUST surface the table to be sure it's parallel to Cutter.

Jazzcnc when you say "MUST surface the table to be sure it's parallel to Cutter" you mean that the spindle should make a full pass over the cutting table and milling the table surface ?

Jazzcnc wrote
NOW what is VERY VERY important is that the X axis~(long axis) rails are on the same plane and not in twist.!! This is where all your efforts need to be concentrated on getting correct. The Bed could be Banana shaped and slopping at an angle it doesn't matter because after surfacing it will be flat and parallel to cutter BUT ONLY if the X axis rails are on the same plane. Any errors in this department affect the whole machine.

Several ways to ensure this but really only 2 that are realistic to the DIY builder. These are Epoxy levelling or adjustable top rail and careful measurement.
Epoxy is probably the easiest because it doesn't require accurate straight edges or equipment.! It's just more time consuming because of prep to surface to ensure clean and setting up dam walls and bridge etc . . .Plus it's messy and requires clean up afterwards!.

Here i have two question

1.when you say "adjustable top rail and careful measurement" you mean the X ( long) axis rails should be adjustable right?
2.when we talk about self leveling polyester epoxy, is it specific epoxy or common marine polyester can do the job. Should i need a primer in order the epoxy to bond with the metal?

Jazzcnc wrote
I recommend Digital drives with good resonance damping built in if building from steel. Also fill the Tubes with sand for best affect.

When you say "digital drives" you mean the motor drives. I reminds you that i will use 400watt yaskawa servo motors Sigma II generation, and i plan to put all the electronics not under the cutting table but to a separate enclosure in order to avoid vibrations for the electronics.


My main concern of using epoxy is the aging and the temperature effect to the table. I am talking about contraction expansion. The machine will be placed at my basement where i have temperatures from 8 ( winter ) to 26 ( summer ). Would that be a problem? What will happen if one day i decide to move the machine to another place. The truth is that epoxy look a good and easy solution, on the other hand i don’t fell good if i don’t have the ability to adjust. Also do we know how epoxy reacts. It is more than sure that epoxy doesn’t have the same contraction expansion ratio as steel. I have heard that pro builders that use cast iron, leave the metal for aging for 10 years...
Thanks again everybody. If anyone has something to suggest i am anxious to hear

[JAZZCNC]

2. For the rails support beams I am between these profiles
80X80 4 mm
80X80 5 mm
100X100 4 mm
100X100 5 mm
and for the table structure
80X80 4 mm or
80X80 5 mm
i want your advice

Any of those will be fine. Personally If mainly wood use then I'd go with 80x80x4 and save some money has it will be plenty strong enough.

Jazzcnc when you say "MUST surface the table to be sure it's parallel to Cutter" you mean that the spindle should make a full pass over the cutting table and milling the table surface ?

Yes exactly.

1.when you say "adjustable top rail and careful measurement" you mean the X ( long) axis rails should be adjustable right?

Yes exactly.

2.when we talk about self leveling polyester epoxy, is it specific epoxy or common marine polyester can do the job. Should i need a primer in order the epoxy to bond with the metal?

It must be solvent free epoxy to avoid shrinkage. No primer is needed just very clean oil free surface also best if rough surface so epoxy binds to it better.

When you say "digital drives" you mean the motor drives. I reminds you that i will use 400watt yaskawa servo motors Sigma II generation

Yes sorry forgot you where planning to use servos.

My main concern of using epoxy is the aging and the temperature effect to the table. I am talking about contraction expansion. The machine will be placed at my basement where i have temperatures from 8 ( winter ) to 26 ( summer ). Would that be a problem?

I've not had any problems with heat/cold, My workshop can go from -8 (winter) to 30 (summer thou rare here in UK) so don't think you will have a problem.

What will happen if one day i decide to move the machine to another place.

Nothing will happen everything will remain the same. Remember the Epoxy is not to level the machine.!! . . . It's just so the two rail top surfaces self level on the same plane.
To give an massively over exaggerated example.!!
Imagine the rails or the full machine before applying epoxy are not on level surface, lets say 10deg slope. When you apply the epoxy to rails they will self level on the same plane. Looking at the epoxy From the side it will have 10deg taper.
If you then move the machine to a level surface the rails will slope 10deg . . BUT . .They will still be on the same plane provided the frame is stiff and doesn't twist when you move it.
This is why My machine works in vertical position(15deg angle) because doesn't matter if the rails or bed are at an angle only matters that the two rails are on the same plane.

The truth is that epoxy look a good and easy solution, on the other hand i don’t fell good if i don’t have the ability to adjust.

The idea of epoxy is so you don't have the need to adjust.! . . BUT . .If you want the best of both worlds then have adjustable top rail and epoxy the surface has well. . . This way you can fine tune using shims if you feel the need.

Also do we know how epoxy reacts. It is more than sure that epoxy doesn’t have the same contraction expansion ratio as steel. I have heard that pro builders that use cast iron, leave the metal for aging for 10 years...

I've been using the Epoxy method for 3-4yrs now and I've not had any issues but if you want to be 100% sure and follow tradition then leave it to set for 10 years. . .Lol . . .( By which time we will have moved on to making DIY Star trek Replicators . . )

To be honest, as my english arent good , i dont understand excactly what you did
When you say "I put layer of plastic between rails and plate" what you mean? what kind of plastic ?

The layer of plastic is just a barrier to stop the top rail being bonded to the mounting plate so it can be removed. When the Epoxy putty has set hard the rail is unbolted and plastic barrier is removed and thrown away. The plastic can be any type, old carrier bag anything. Someone suggested to me taping the rail with parcel tape which I did try and does work ok.

when you say "between rails and plate" what do you mean? Your rails rest on a plate or on a square beam ? Sorry for asking but i dont get it

Look at the picture Eddy posted and you will see the plates which the rails bolt onto. Epoxy putty is then spread on these plates, then piece of plastic placed between rail and epoxy to stop bonding together.
I then set the rails on the same plane and parallel with a combination of temporary shims and adjusting bolts. Effectively the Epoxy putty is acting has a Permanent shim when dry.

Hope this makes more sense.?

[Boyan Silyavski]

First of all thanks everybody for the participation to the thread.
Next i would like to introduce some of my conclusions and ask some things about all these that i have already read

1. I beam will not be used
2. For the rails support beams I am between these profiles
80X80 4 mm
80X80 5 mm
100X100 4 mm
100X100 5 mm
and for the table structure
80X80 4 mm or
80X80 5 mm
i want your advice

Look from what you started and where you jumped- 100x100x4 and 100x100x5

Read again what Dean /jazzcnc/ told you, first be sure for what you use it mainly and then decide on the thickness. Go to your local metal shop and check for your self about the 100x100x5 and 80x80x5. This is way too much. Ok, people use them but for builds that intend to cut mainly aluminum and so.

My main concern of using epoxy is the aging and the temperature effect to the table. I am talking about contraction expansion. The machine will be placed at my basement where i have temperatures from 8 ( winter ) to 26 ( summer ). Would that be a problem? What will happen if one day i decide to move the machine to another place. The truth is that epoxy look a good and easy solution, on the other hand i don’t fell good if i don’t have the ability to adjust. Also do we know how epoxy reacts. It is more than sure that epoxy doesn’t have the same contraction expansion ratio as steel. I have heard that pro builders that use cast iron, leave the metal for aging for 10 years...
Thanks again everybody. If anyone has something to suggest i am anxious to hear

Don,t get me wrong, but your main concern should be squaring the rails in one plane. And choosing square supported rails, not roundish.
I assume you don't have even a straight edge and you worry about contraction and expansion. First think do you need such an accuracy, then do you have the actual means to measure it, then how much is the cost of the tools to measure it...
For wood and plastic and occasional aluminum you need much lower accuracy than you are contemplating.

I mean relax, and be careful not to make some obvious mistake. Like making a cnc for another kind of job. remember the old saying: " The machine is strong as its weakest part". I constantly meditate on this when i catch myself overbuilding

[EddyCurrent]

Just grabbed these out of a video I saw if any use



details are here 3D Model of CNC Router c4d, obj, 3ds, fbx, dxf, skp, iges
and it looks like they had to add some triangulation to the legs after these photos

[ba99297]

So far thanks everybody for your answers
Your advices keep me away from mistakes that i think could cost me money time and poor final result
After all these answers, i decide

to use part of Silyavskis' table plan ( for part of the table that the X rails rest on) .
Not to use the I beams
Not to use adjustable beams for the X axis rails and go on with the epoxy solution.
This choice means that the table is solid as rock. So before i go on with the 3d design i want your advice about the table diagonal reinforcing.
Here are some autocad plans. They represent side view of X axis. I design 4 solutions ( A,B,C,D )
The upper yellow line represents profiled rails, and the green color is adjustable legs
Tell me your opinion.
I haven’t decide yet if i will go with 80X80 or 100X100 box section. It depends from the cost. The following plans are made with 80X80 box section
Thanks for your time

[EddyCurrent]

I like B but not everyone will

[Boyan Silyavski]

I like A but if i were you, would turn the 4 diagonals 180 degree/ mirror them upside. That will separate on smaller sections and support even further the X rails support + when pushed from upside will make a stretching force to the lower beam, not pushing, as it is now.
I mean instead of MM WW

If full height is desired, as Eddy says B is best, simple and strong + the diagonals will stretch again the lower beam, if pushed from above. And we all know steel can not be stretched

[ba99297]

Silyavski before i check for any new post at my thread i design in autocad this



and then i read your post
I think that we are thinking in the same way
To be honest you inspire me for my table plan ( especialy for the rail support beams ) thank you.
Aslo thanks everybody else like Eddycurrent and of course Dean for their ideas
Day after day, thread after thread post after post i feel that the knowledge and the experience of people that willing to help, give me the ability to make a solid machine. You know it is very important to make a step and have no question to be answered. That is what i almost fell now about the table plan. May be some small changes will be done, but the basic consept i think is this.
I will post 3d plans soon
PS A machine that is having rail height at 70 cm from the ground, has any disadvantage compared to a machine that is having rail height at 90-100 cm from the ground?
I will be happy to hear any other advice.
The only question that is waiting for answer is the beam dimensions 80X80 or 100X100 and of cource the thickness
And here i have some 3d plans.
I will come back with another plan a little bit different