In construction new Machine (3 axes)

**txpto** · 04-23-2014, 11:25 AM

Goodnight everyone , after reading a lot, I would say a lot, I decided to build me a 3-axis machine . Sorry for my English , but do not write very well .

I 'll post developments , counsel them to me . I tried reasoning every step I took on the knowledge I have acquired .

You will see that I often reflections based on economic , ie , already with a better profile or with a guide this or that is better and more rigid , but my goal will at all times take advantage of everything that I have , and buy what is necessary and no more. Luckily my disposal some disused materials with which to start that is not bad .

The objective is part of learning and have fun , get to cutting board chipboard up to 16mm ( in multiple passes of course) and not aluminum 5mm fatter . Acrylic or PVC to make molds in balsa wood or some dense porexpan wings to make me model airplanes . Any illuminated sign with LEDs and a wooden base for a ship of that amount.

Always seek the maximum precision within the limits that I have ( and economic means ) .

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Electronic Part :

This is a 3-axis CNC machine , Brushless servo motors and controlled by reducing box obviously reduced resale and some years of operation at the back. will perform disassembly , clean , adjust , etc ...

All this is controlled with variable speed Omrom (not sure if I can say moderators brands) to rectify if you can not do.The only way to control it is with STEP and DIRECTION.

The servo controllers with these signals will typically provide the most control boards amateur market. Specifically I will rely on a Pokeys56U plate , which gives me the opportunity to address control via an IP address. The Board goes directly connected an old wifirouter I have at home and I shall use a Mach3 license that I have yet to buy .

A drives , I 'll connect an encoder with 2048 steps will be in charge of telling the drive axle position . An encoder SHALL return travel around the shaft , but I can choose how many laps I give the encoder for each full axle travel , which can raise much precision, but of course, to be accurate than mechanical is more than enough.

There will be no regulation in full closed loop , as Mach3 never know where the axis ( as in most amateurs machines ) is , but if you at least will have the certainty that if gaps in mechanics, the encoder will move when the axis in question do , therefore I will eliminate the possible backlash between gear motor - coupling - belt ... etc .

Since e is " my thing " ( incidentally if anyone has doubts or electronic questions .... I have at your disposal ) , well , I have more or less validated , ie , by Mach3 I move axes , with accuracy that the system allows me , reading the position of the encoder.

Mechanical part :

This is where the problem comes because I do not have decent tools to undertake such a project. A drill press (with some relief), welder , grinder, and cutting aluminum profile structure . But I do not have router or special machine much less tape cutter , which I had gone so well .

I will use aluminum profile 40x40mm and 80x40mm ( strong ) , and the Y axis profile 80x80mm thick. Let's typical that we all use .
Once the machine , the filled composite profiles + iran sand or any mixture that after curing will Mass and set fastness .

Everything will skid and steely rods 10mm diameter , and the toothed belt transmissions are those that carry steel wires inside loosens not .
According to the manufacturer the system has a repeatability of 0.05mm index , but let me not hesitate, watching the mechanical system leads , but the case is that you get a correct positioning each 0.2mm and I am satisfied at first.

I know it's not the best, but it's what I have .

I 've drawn two possible positions of axis with X axis as a function of the maximum width available to me, ie I want to get an effective workspace 1200x600mm (height apart ) and it should minimize the total space occupied by the machine , since the servo motors excel outrageous and I'm doing different designs to see which is better.
I put two basic designs to see what you look like :

With oblong guides , so I need two motors for the X axis , with their corresponding two gearboxes and two drives, worst choice economically speaking , but closer machine . This system very complicated me the EXACT control both sides without deviations ( added handicap is that the reduction ratio of the gear is different ) .

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And with a single engine option in X axis , with a motor attachment that connects the two sides, and a somewhat larger machine. Now more advisable choice although almost 40cm geared motor assembly laterally projecting lever arm exerts that could break the supports.

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Well, I hope to continue counting poderos more things this week. So far as presentation and I think I could convey what I now need to know where to start.
Greetings to all .

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Z axis retracted. Notice that the intention is that the moving part , is only Kress1050 milling , and aluminum plate , but the rest ( skates and screw thread) , remain fixed in estrucutra . Thus, when I have the engine retracted , not occupy the same site below and can mill parts of a certain thickness .

In construction new Machine (3 axes)-cnc_11-jpg

Here with all the Z flattened route . Obviously , the force at this point is very small, due largely to the large lever arm making structure, but this point is one of the most headaches brought me thus there are many formulas on the Internet , but I have not found anything to help me know which is better distribute the forces between the different points of support ( width between roller axis to X axis height + width skates axis leverage point to point motor) ...