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ramsbury
15-01-2014, 08:26 PM
Well folks.
I have decided to Build a Stone profiling machine.
After looking at hundreds of machines online and at stone fairs and shows decided they are Either too small for what I can afford. so expect to build a machine to the same size of commercial machine for the same price as a smaller machine.

Reason to increase production.

Began last weekend
Buying the Steel..

Machine Dimensions are:

2700mm long 2440 x axis.
1350mm wide 1220 Y axis.
1500mm high. 450 Z Axis.

Steel box section rectangular 120mm x 60mm x 5mm..

Nema 34 1600oz pair on X to drive two R&P and on Y to drive a single ballscrew Undecided what size,, on Z probably 820oz simply to have the guts to drive a 3kw motor with a diamond profile finger into stone with Cuts at 10mm deep Max per pass, without dropping steps.
commercial hexagonal rails and profiled rollers on x because of stone dust and water
still looking for a supplier.

THK rails for Y and Z

mainly based on a 3 axis Stone saw But with a spindle cutter instead of a Disk.
the Table is my design which will take 500kg without too much deflection.

the maths works out at 0.45mm deflection at 3 metres unattached so should be able to achieve .04 at least after welding legs on.


Cut the steel two days ago.
Ground the ends and started welding today.

kingcreaky
16-01-2014, 07:33 AM
sounds like you have it all worked out! we expect plenty of pictures

ramsbury
19-01-2014, 08:12 PM
1132411325 Here are the first two Pictures Started welding last wednesday and Saturday, didn't realise how much welding there is in it, Ive still got corner holding plates, two middle braces, 4 more legs, Diagonal braces and of course the Runner supports for the rails. then Ill be ready to start making the Gantry. I was thinking Brake pressed or welded steel Made boxes and steel across the gantry itself to take. Rails which will be profile with carriage.

Although the frame will easily support 1 ton of stone It will also be bolted to the Concrete floor where it will be placed.

Input would always be welcome.

Lee Roberts
19-01-2014, 08:15 PM
Looking good, subscribed...

ramsbury
19-01-2014, 09:22 PM
Has anyone any experience with R&P integrated profile rails?.

ramsbury
26-01-2014, 09:18 PM
Decided to go with servos instead of steppers

george uk
26-01-2014, 09:25 PM
Hi

what was the deciding factor, ?

ramsbury
28-01-2014, 08:15 AM
Hi

what was the deciding factor, ?
decided to Go with Servos. steppers just don't have the Continuous torque for the length on the machine,thee is also the possibility of extending it. Most of the stone I shall be cutting will be over 1700mmlong x 500mm widex 100-300. now toying with a 4th axis to make columbs instead of building another machine.

george uk
28-01-2014, 10:20 AM
hi


thee is also the possibility of extending it.

If so, you may wish to consider the rotating ballnut design for driving your X


now toying with a 4th axis to make columbs instead of building another machine.

Have you played much with the software, because there are options for 2 sided machining, and it would be a lot easer to do columns with 2 sided machining than rotating it. 4th axis is well worth doing, but if you specificaly want colums, or anything of that weight, you would be better doing a vertical machine just for them.

I would have a play with some of the software, meshcam ( free trial ) is a good bit of software to start with if you want to see what 2 sided machining can achieve, the learning curve of the software is reletivly easy as well

MeshCAM - CNC Software - CAD/CAM Software (http://www.grzsoftware.com/)

ramsbury
28-01-2014, 09:10 PM
Definatly sticking with R&P can get it to .04 most of the software I have used is lettercutting on various machines Ive looked at vertical machines and they are simple to make.. 4 axis is a secondary thought but may still.
so will take your advice and have a look at some software, I suspect I shall have the machine finished in about 4 months at the rate im going.

george uk
28-01-2014, 10:48 PM
meshcam is a good example because it lets you play about with machine settings to visualise how the final cut will look, and the cutting strategy program is very easy to understand, and allows you to visualise the cutting paths. i have looked at but not used sheetcam and some of the other more complex softwares, even to the very expensive. They all have a massive learning curve. whereas, if you cutting/profiling stone, especialy complex 2.5 D profiling into stone, mesh cam is very easy to learn

gavztheouch
28-01-2014, 11:26 PM
Wow this going to be quite some project. What is the spindle/cutting tool like, does it uses fluted router bits to actually cut the stone or does it grind away at it with an abrasive stone. What horse power will the motor need to be.

There is a chap close to me who does a lot of work with cnc stone cutting, his machine hangs down from the ceiling and I think I remember some of the axis being belt driven?

Good luck

ramsbury
29-01-2014, 05:02 PM
Ill def have a look at the software most software ive used is for 2D I have to jump,,, My original intention was to build a machine 2 metres x 1 metre with a 200 Z but found my budget is better than I thought so Bigger it goes,,There are various long V cutting bits for granite now on the Market But a decent 3KW spindle will cut through anything as long as the feed rate is correct Gooing to 4.5 KW or higher doesn't make much difference these are usually to drive Long bits or large blades.. Diamond has a finite working speed if too high it burnishes the Bits exactly the same as Using Carbide bits on granite and polishes the diamond flat.. the only machines ive seen belt driven are small 2D cutters.

george uk
29-01-2014, 07:46 PM
Hi


a decent 3KW spindle will cut through anything as long as the feed rate is correct Gooing to 4.5 KW or higher doesn't make much difference these are usually to drive Long bits or large blades

spindles have efficiency curves, a lot of the 2.2 - 3 kw ones are tuned to perform between 18000 and 22000 rpm, below that speed, they don't have enough torque,


Diamond has a finite working speed if too high it burnishes the Bits exactly the same as Using Carbide bits on granite and polishes the diamond flat.

a lot of the stone bits are low rpm, and some of the spindle i have looked at are High kw but have the torque at lower rpms, its one of the reasons i was considering a belt driven spindle, or a servo as a spindle, i still haven't made my mind up yet.

ramsbury
30-01-2014, 08:09 AM
I understand the Torque reduces. and slower Cutting speeds are needed for harder stones. so faster cutting speed is not a good idea .
there are many types of stone grinding spindles 3KW Grinding spindles at 5000 RPM are available which means Oceans of clean cold water any loss of water means a new Grinding bit .
Though I have been quite surprised as of looking at the Technology of some of these spindles many are designed grind and polish through Granite worktops with high KW spindles. so wouldn't have a problem with Sandstone or limestones. such as Portland, Purbeck and soft stones like Ham and Bathstone.