Accurate Strong Gantry

[Boyan Silyavski]

The bottleneck of this project will be the spindle. So a certain realism should be applied when designing the machine.

Why? I agree that you could build a frame any style for a mill. And make it rigid enough.

You have exactly 3 general choices:

-use cheap Chinese water cooled spindle up to 3kw /2 phase/ or even bigger 4-5kw. 18-24k rpm. The problem is that the bearings of the spindle are not made for steel machining though from time to time you could do that. No low revolution power. I would never try to use mine spindle on steel

-Use the BT30 spindle 8000RPM from ali express. Now this spindle screams for column Z. Otherwise how you will mount the motor and the tool change and balance the weight? Not possible. Not so cheap though as only the spindle side will be >2000eur with the motor and changer. Not so fast for High speed machining


-use the design like the german gantry machine example and add bigger than 10kw spindle. That will work best for what you want but the spindle will be very expensive.


So as you see, it is like i said before- you want steel -you make a mill, you want up to aluminum -you make a router. You want both-yes it possible, but prepare some $$$, cause you will need BIG motor to be fast and at the same time to has power on the low rpm.

[JAZZCNC]

I agree 100% with everything Boyan says regards spindle but it just doesn't stop at the Spindle to do this correctly.

The massive build required to cut steel correctly with acceptable accurecy and repeatabilty affects the linear motion and motors used plus many other things. (Has Boyan knows well.!!)
Wood's plastics etc need higher feeds to cut correctly so this means motors which can handle high Mass of heavy gantry and still allow higher feeds.
This will mean servos to do it correctly. Servos require high pulse counts so this means quality motion control cards and control software. The list and expense goes on and up.

Has Boyan will no doubtly be very aware of this quickly gets expensive and requires more attention to detail and selection to get it correct.
Even then there will always be a compromise in the machine some where.? One machine can't do everything to high standards without being very very expensive.

IMO you will be much better building a router that will cut everything in it's capabiltys, Ie woods,plastics etc to a high standard.
Then buy a milling machine at later date that will do and give the same high accurecy and repeatabilty with Aluminium and Steel etc.

The chances of failure or dissapointment for large machine to cut steel is very high and the extra expense trying to do so easily wasted. Much better to be realistic about this just build a strong functional router and save the money you WILL waste trying to build all round machine then put it to buying a milling machine.

[vargai]

IMO you will be much better building a router that will cut everything in it's capabiltys, Ie woods,plastics etc to a high standard.
Then buy a milling machine at later date that will do and give the same high accurecy and repeatabilty with Aluminium and Steel etc.

Years ago two gentlemen visited us from a UK company Built Offsite to clarify the details of some modular building.
Being interested and reading some books about inventors and Technics I told them that the industrial revolution did not begin accidentally in the UK.The only fortuitous was just they came from Shrewsbury where around the industrial revolution had begun.
You are enterprising and advised to reach the high technical level where you are now.
I hope I am enterprising enough no to stop at the difficulties and advised enough to perceive the realistic factors.

The cost is vulnerable issue and the question is over and above: what is different between machine and good machine and very good machine. Purpose+Design+cost+used time+effort and so on -there are many factors are too see and specify the scope.

[GEOFFREY]

Years ago two gentlemen visited us from a UK company Built Offsite to clarify the details of some modular building.
Being interested and reading some books about inventors and Technics I told them that the industrial revolution did not begin accidentally in the UK.The only fortuitous was just they came from Shrewsbury where around the industrial revolution had begun.
You are enterprising and advised to reach the high technical level where you are now.
I hope I am enterprising enough no to stop at the difficulties and advised enough to perceive the realistic factors.

The cost is vulnerable issue and the question is over and above: what is different between machine and good machine and very good machine. Purpose+Design+cost+used time+effort and so on -there are many factors are too see and specify the scope.

I do not usually comment on this type of thread, but PLEASE listen to Jazz. He knows exactly what he is talking about and trying to stop you spending money needlessly. Build a good quality router for softer materials and buy/convert a mill for steel. That is my lot, I shall not comment again in this thread. Good luck with whatever you decide. G.

[vargai]

I do not usually comment on this type of thread, but PLEASE listen to Jazz. He knows exactly what he is talking about and trying to stop you spending money needlessly. Build a good quality router for softer materials and buy/convert a mill for steel. That is my lot, I shall not comment again in this thread. Good luck with whatever you decide. G.

Thank you and you are welcome any time.

[Ross77]

Normally if someone says that it cant be done then that is like a red rag to a bull and I try to come up with a solution, but now you have brought steel into the equation then I would agree with the others that it will be really difficult as the requirements are at opposite ends of the spectrum.

If it was Diy the you could compromise on the design and use the machine to the best of its abilities but you seem to be saying that it will be a commercial use so that wouldnt really be feasible.

If you did proceed you will need to two spindles.

1. Low speed with high ridigity and power at low speed for steel.
2. High speed and power at high speed for ali.

You would then need 10mm pitch ball screws on high power servo motors with high resolution encoders to get the accuracy. Etc etc.

It can be be done but like the others have said it will be expensive and you will still end up compromising the design. It may well be cheaper and better from a production point of view to build 2 specific machines. Good luck

[vargai]

It may well be cheaper and better from a production point of view to build 2 specific machines. Good luck

IMO you will be much better building a router that will cut everything in it's capabiltys, Ie woods,plastics etc to a high standard.
Then buy a milling machine at later date that will do and give the same high accurecy and repeatabilty with Aluminium and Steel etc.

Sorry for late answering. I could have placed this post to a general thread since by going through my one the searching on the good design led the doubt about the primary aim.
Reading the posts after my latest design I recognized or at least felt the generally weak points. Sorry for seeming stubborn. It is not meant to happen. My tenacity is all about my goals and not the way and method to reach it. It is not easy to abandon a main intent and to say right away yes, or no.
So thank you all who involved for your efforts and advice in highlighting my weakness.
I hope I do not have to turn my back on metal and will be able to build a good router for Al and other softer material.

[JAZZCNC]

Years ago two gentlemen visited us from a UK company Built Offsite to clarify the details of some modular building.
Being interested and reading some books about inventors and Technics I told them that the industrial revolution did not begin accidentally in the UK.The only fortuitous was just they came from Shrewsbury where around the industrial revolution had begun.
You are enterprising and advised to reach the high technical level where you are now.
I hope I am enterprising enough no to stop at the difficulties and advised enough to perceive the realistic factors.

The cost is vulnerable issue and the question is over and above: what is different between machine and good machine and very good machine. Purpose+Design+cost+used time+effort and so on -there are many factors are too see and specify the scope.

I'm struggling a little here to decide if we have a language barrier thats getting the translation a little muddled or if you are saying "Get stuffed" I'll do it my way regardless.?

Hope it's just language differences but honestly I don't care if not.! . . . Because if your stupid enough to go against good sound advice from several experienced people then more FOOL you and I DON'T wish you Good luck as that would be encouraging someone to waste money and being a born & breed Yorkshire Man I wouldn't encourage even a FOOL to do that.. . . . . . Just like I won't waste my time or hard learnt experience on FOOLS.!

[vargai]

I'm struggling a little here to decide if we have a language barrier thats getting the translation a little muddled or if you are saying "Get stuffed" I'll do it my way regardless.?

Have I made something wrong?
I have started this thread and collected all the information that is necessary to make decision.
I have not buy anything and not gone any direction yet .
The only thing I do I try to make out these info that is just slightly more then just listening.

[vargai]

-Use the BT30 spindle 8000RPM from ali express. Now this spindle screams for column Z. Otherwise how you will mount the motor and the tool change and balance the weight? Not possible. Not so cheap though as only the spindle side will be >2000eur with the motor and changer. Not so fast for High speed machining

I have just went through the sites of motor, spindle, etc and they are expensive even from China.
Ie.only a BT40 spindle would be 2000 EUR in my hand with VAT,etc.
In my present eyes it is too much for 30 kg engineered steel and if I went with this I would make it myself.
Regarding the power I think I would satisfied with about 4 kW
But the main issue is not this and thank you to summarized.