Surface grinder double column

Traian

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Hello everyone my name’s Traian and I would like to asking some information about my project i want to bulid a surface grinder double column 1700mm x1000mm wide with gantry move and im struggle with found information about what drive system is good to chose for this type, my intentions was to use nema 34 1700oz with planetary gearbox
For x axis each column have his motor connected to helical rack z axis each column have worm gearbox connected to the middle of gantry driver by a motor and y axis only a motor with planetary gearbox, problem is never experienced with hybrid stepper motor and mach3 breack border and mpg hand wheel, not, has to do smooth and slow x axis teavel ,i want to use as manual as well if need,
Problem is if i want to use just x axis automatic back and forward mach3 I don’t know if does or is other system to do my machine thanks and waiting for your suggestions thanks
 

JimDawson

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Welcome aboard Traian! An interesting project.

Are you going to build the machine, or are you starting with a gantry type surface grinder? A 1700 x 1000 mm surface grinder is very large. Is this going to be a moving gantry machine? If a moving gantry machine, I think it will be very difficult to make it stable enough to make a good finish on your parts, all double column surface grinders have a moving table with a fixed gantry.

Is this machine for grinding metal? Or some other material?

It is too early in the project to make a decision on the motors and gearboxes. I think you do not need to use any gearboxes. You need to know the mass and speeds of the moving parts before you can determine the power requirement. But I can say now that a NEMA 34, 1700 oz stepper motor is not a good choice, they don't work well under any condition. I had a machine in my shop with a 500 Kg table, I was moving it at 15,000 mm/min with a 1200 oz NEMA 34 stepper. If possible, AC servos or closed loop steppers would be a much better choice.

Running it with Mach3 is no problem.
 

Traian

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Thanks first for replay more like base is that size I didn’t do any drawing but i did some simulation on a timber i can show to be easy what i mean yes i want to grinding metal, lathe bed millings parts.... reason why asking for motor gearboxes was before to start to build anything in steel and cast iron o don’t want to modify before as much as i can
For x axis linear motion i will use RG series 30 linear rails with roller bearings 2 per column
Thanks
 

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pontiac428

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Planetary gearbox = backlash
slow-twist lead screw = torque increase plus resolution increase
 

Traian

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For x axis i use helical rack and pinion between rails and there was straggling with idea about synchronisation 2 motor for each column and z axis when said about worm gearbox fron each column,one motor in the middle drive,about motor thinking about that nema 34 but hybrid closed loop, but if not a better choice i will not no for that, how you said i still long way till there first is the machine it self frames....etc in the picture will see how my head will tilt for angles in case i want to do v way
 

JimDawson

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It is not possible to move the gantry and do good surface grinding, too much flex and vibration in the system. You must move the table. Your design would work OK for a CNC router, but not for surface grinding. When surface grinding you need to be able to hold 0.001mm or better. This requires a lot of mass in the system and must be very rigid.

Here is an example of what I am talking about. With some substantial modifications this router could be made into a double column surface grinder, but this is the basic design that I am suggesting. The table moves on 50mm rails, the main frame is a heavy torsion box, the Y axis is supported on heavy 250mm square columns that are rigidly attached to the main frame. This is a 1200 x 2400 mm machine. About 2500 Kg, not really enough mass for a surface grinder. The round rails are not the best for machines today, the profile rails are much better, but did not exist when this machine was built.

1590514596073.png
 

Lo-Fi

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Getting that accurate is going to be hell whether it's the gantry or table that moves. Agreed with the comments above about moving the gantry too. Linear rails are all very well, but you need them mounted to something really flat and rigid to get them straight themselves. For which you really need a planer or surface grinder... I know: the irony!!

I've seen a few YouTube videos where people have welded up frames and messed about with shims, but they seem to end up with lumpy rails. Getting 4 aligned true, level and flat along their length is quite a mission without a larger machine tool. Even 2 of that length is a big ask.
 

Larry$

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I have to agree with the others. You will likely find that the moving gantry will have way too much flex for surface grinding. I have a moving table fixed gantry CNC router. It is designed for wood based materials and weighs about 14,000#s. It is all ball screw servo driven with large profiled recirculating ball bearing rails. Well designed for wood, likely not good enough for metal grinding. It might hold .002" tolerances but you need .0001 for surface grinding. Consider sending your parts out to a shop that has the equipment to do it correctly.
 

Traian

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Thanks guy for good advice,Lo-Fi thw way i want to do is not exactly what you saw, for base i want to use this c channel and i will draw later to show how i will use c channel and each side i will use 200x 1700mm and 20 mm thick each side of frame welded and make like a lip for each rails in the end to be straight and yes i will plan surface grinder all base, the type of rails I’m gonna use will be roller heavy load 30mm rails with heavy block with roller ball and eack blocks have 131mm and the foot of column will be a steel plate 20mm thickness 300x 200 and the column i want to custom 250grade cast iron 160x110
 

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Traian

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What is with green will be grinding flat surface. Thanks
 

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