Thank you Wiwatto.

Thank you Rick. I will post some details of the sawhorse.

Parts all painted and re-assembly begins
 

All fasteners were put in place loose. The wheels and dampers were installed and the set was levelled. I squared the assembly diagonally and tightened the first and last table beams. There was about 8 mm variation in the width of the machine on the rail rest beam. With flat belt tightener I narrowed the distance and tightened all the table beams while measuring the diagonals on the frame. There remains about +/- 2 mm variation which will be adjusted during the rail adjustment. Then I tightened the transverse frame bolts.

Attachment 6786

Placed the rails and X axis echain support in place and scraped the paints on the contacting face of the rails.

Attachment 6787

This is the detail of the wheel and the damper.

Attachment 6788

Great job, Nader. I really enjoy reading your build and photos!

I waiting your progress

For me, Absolute confirm " Your are my inspiration " MechMate

Thank you again all done in this forum.

Wiwatto, you have told us enough of your inspiration, now we want to see your progress! :)

Thanks john.

Rick, here is the details for the sawhorse. The original credit goes to Fabrica. His posted pictures inspires lots of ideas for sawhorses.
Attachment 6806

See here for more sawhorse detail.

Alan,

Sorry for the mix up. I stand corrected. The idea was yours but it was in Fabrica's thread. My MechMate picture files are sorted by the name of the initiator, e.g. Yuri, Irfan, AlanC... therefore I only referenced from the folder. I should be more careful when referencing.

No problem, at least my wacky idea was able to help someone :)

I am not an engineer, but I am a bit worried about your placement of your damper/foot, is there not a danger of that plate bending once the gantry, support board and spoil board are in position (I also tend to climb up on my machine quite a bit, but then again I am on the wrong side of 100kg's)

Maybe you could think about adding a brace as shown below, that should not hinder your adjustment of the dampers/feet.

Attachment 6826

Hi Gerald

After "ATIFEH ( Nader )" finish his job i will post some picture in 2 years ago, that started building 1st MM. Nowday i have plans to rebuilding it again. Also i have something i never told your are "YOU ARE MY "HERO" since i start to interesting CNC Machine.:):):D:D:):)

Yes "ATIFEH" you please post your progressing. :):):)
I like the way your work

Alan,

Thanks for the idea. I should have done that before but I have to figure out a way to add this brace without dismantling it, since I am not good at welding vertical joints. The plate is 10 mm thick and only 32 mm projected.

If Gerald and everybody else agree and feel suitable, lets allocate a thread for different jigs, fixtures, clamping and work holding systems, intermediate storage systems and likewise that the members have made .

Nader,
Alan is right to point the need of reinforcing the legs. If you are not confident with your vertical weld, I would suggest you "joint-up" many spot welds to form a strong weld. That what I'll do ;)

Cheers

Ken

Bending stress = Bending Moment (N.mm) / Section modulus (mm3)

For cantilever beams:
Bending Moment (N.mm) = concentrated load (N) x distance (mm)

Assuming that the total weight of the machine+mdf boards+workpiece+myself =12kN, each leg will take more or less around 4000N of load.

With 18mm distance from the cantilever fixed point, the bending moment will be:
4000N x 18 mm = 72000 N.mm

The section modulus on X-X axis for a 40x10 mm hot rolled strip will be:
(40x10^2)/6 = 667 mm3

Therefore:
Bending stress = 72000/667 = 108 N/mm2

For mild steel (st37) the median bending stress limit is 290 N/mm2 > 108N/mm2

Alan, Ken,

These calculations were meant for only one purpose. To ease my conscious, refraining from a vertical welding with unsuitable electrodes, 100 mm above the ground, a lot of paint scraping and paintworks to be mended later!

I had a cold this week, so I stayed at home and worked on the electric wiring. Here is a zip file containing: the wiring diagram (dxf) and the simulation (ekts).

Attachment 6907

Earlier this week I bought a Q2HB68MG bipolar driver (www.bsjd.com) for testing. These drivers are microstep, 24-80V and 0.5-6A. I have never before used bipolar motors, so this was an exciting experience.

I had 2 types of motors available:
4 wired 4.2 N.m, 6A/phase, 2.4V, 0.4Ohm/phase, 3.4 mH/phase
8 wired 2.2 N.m, 4.5A/phase, 2V, 0.45Ohm/phase, 1.7 mH/phase

You can see the pulse generator I built with a NE555 with jumper selectable capacitor rows and a pot. It gives 0.8Hz up to 10.9kHz pulses.

Also note the power supply unit I use for bench testing. Tied to a 24VAC, 250VA transformer which gives approximately 36VDC.
Attachment 6908

The driver was set to 1/5 step. The 6A motor which has higher inductance, topped up the frequency and the rotor could not be stopped by hand. The lower inductance motor (4.5A) would not turn beyond 7.76kHz in serial wiring but did the full 10.9kHz in parallel mode.
Since maximum 3 motor will be working simultaneously, I think Mach could manage turning these three.

Just a casual note: Mild steel and ST37 are not quite the same thing. I agree with about 290 N/mm2 for mild steel, but you may be interested to know that ST37 was a German abbreviation for "Steel 370 N/mm2" :)

We could have a long discussion on stress calculations, but just some quick observations:
- Most times, in the frame of the CNC machine, we are concerned for stiffness, and not so concerned for risk of failure.
- But, at the support feet, often a spring element (low stiffness) is used for damping/isolation - you can claim that you have an isolator :)
- But, if it were a true isolator, then you need to design for fatigue. The fatigue limit of mild steel is about 50% of the upper stress limit. (Plus you have a weld at the highest stress area) :(
- But, the loading for the fatigue condition will not be 12kN - subtract your body mass :)
- etc.

Engineers sometimes calculate, sometimes use instinct . . . . .:D

Gerald,

Unfortunately the term mild steel has found a very wide definition by people who are paid to complicate things! Long ago, it was only meant for the cheapest structural steel. Now there is a whole range of disputes around its chemical composition and/or its strenght. To make it even more fun, mild steel is now even graded! like Grade 250, Grade 350, etc.
These standards and there desparate attempt to adapt to each other make me crazy. To tap a M6 thread, DIN says drill 5.0mm, ANSI says drill 5.15 mm (or at least this the the preference for my MDT6). Low quality drill bits have some wobble, so I drill 4.9 mm!

You and Alan were right. It is the stiffness concern. I agree and believe that this little brace would give the construct a lot more rigourous look. And about the failure, actually I was thinking "how would a 36mm tab be bent when it is supported on some sort of polymer?"

Just a thought. If you have difficulties with vertical welds, a brace like this could alleviate them. Drill for the two bolt holes and then you only have to horizontal weld it.

Or this:


. . . . but in real life I would leave it as it is now! :)

Thanks all for the ideas. For now I will leave it as it is, as Gerald suggested, but in the future I will use Allan's Idea which is the most simple and yet does not confine accessibility.

Greetings to all,

These past weeks, besides a hectic period of work, mostly I managed some other activities.

Bought the whole lot of electrical parts and cables for the next stage.

Bought the computer but have not set it up yet.

Designed a whole new set of power board, 12/5 V board, pwm to 0-10 V and a more compact breakout board (since I have to use two boards). Had them printed on film and made the bare boards.

Attended a one day course for programming the DELTA VFD-E, which I learned how to interface it with external signals. These VFD’s have a lot of potential and I think it is worth learning the plc section of it.

I will be revising the electric schematic which will be posted after completion. Now the VFD will work in two modes, 1- which receives the start and pwm from MACH. 2- a switchover which overrides MACH and gets the RUN and rpm manually, through its detachable mini panel.
I decided on this switch in order to execute the warm up sequence as devised by Mr. Richards without entering MACH. I would not be using the reverse turning, as my spindle is an ER20 collet. Reversing will probably loosen the nut and be quite dangerous. Please tell me of any possible uses for reversing the spindle. The only use I could imagine is for tapping.


Besides, these were the progress made on the machine:

Mounting the racks:
As you have noticed, I use 35mm, M6 screws to hold the rack at a distance from its final position. This provides enough room to strip the double sided tape. For the X axis a middle support is used as well. Then the screws are turned and the rack is elevated to about 2mm below its final position. This facilitates the positioning of the rack and provides a means to once again check the linearity of the rack against the rail. After binding the rails, the screws will be replaced with M6x25mm.
Attachment 7115

Attachment 7114

Attachment 7113

Z plate:
These were the original plates for mounting the spindle.
Attachment 7116

I revised them to incorporate several holes for: attaching a Z echain, bracket for home and limit switch, a moveable dust collector attachment, additional holes for relocating the spindle plate:

Attachment 7117

Attachment 7118

Arrangement for the tension springs.
Attachment 7119

Attachment 7120

Nader: Very nice! Thanks for the great and instructive pictures.

Thanks Joe,
Hope they are helpful.

Besides the VFD and the drivers which I bought, I made two buffered breakout boards and a 12/5 V regulated power supply.

Attachment 7205

I wonder if I could use the 12V for the PWM to 0-10V board for the VFD, as the 12V and the 5V have common grounds. Any comments?


I decided to install an echain for the Z axis which might prove useful in the future; an air hose for a high speed turbine spindle, a water colled spindle or … The size is 25x30mm.
Attachment 7206

Attachment 7207


This is the configuration that I use in my gearboxes. A M12 bolt through a bronze bushing, 13mm high. The gearbox stands clear from the support arm by about 1mm which could be less if i grind the bushing.
Attachment 7208


I tried the standard MechMate 35 turns, 2mm wire, 16mm OD, with elongated length of 128mm, which happened to be unsuitable. While cranking the Z plate down manually, at a point the pinion slipped off the rack. I made a spring with 16 turn, which is very hard to expand and the slipping was eliminated. Now I have to optimize the length of the spring. I suspect this problem is due to slope of the spring and the horizontal vector of the force.
Attachment 7209

Attachment 7210

Here is the detail of the spring assembly:
Attachment 7211

Nader, very interesting build. Please keep the pics coming!

I changed the Z motor spring to 30 turns of 2.2 mm wire, 16 mmOD. Still slipping. Reduced the number of turns to 23 and it works fine.
I guess the below picture shows the fault. The point of effect of the spring is very much near the pinion axis, not providing enough leverage. The spring should be attached farther up.
Attachment 7254

The components and arrangement for the Z axis home and limit switch.
Attachment 7255

Attachment 7256

Attachment 7257

Details of Y axis echain:
Attachment 7258

Attachment 7259

Attachment 7260

Nader, that y-car design (bolted rectangle) was used by ShopBot and it was not a success. The major cure for the weak rectangle was to add a second y-motor. Another cure was to add a plate over the rectangle - link

Gerald,
Thanks for the hint and the link. I studied it but could not comprehend the problem. What was the problem with the ShopBot? What stress condition made it faulty?
Thanks.

Nader,

Your machine is looking really good.

A 5-minute sketch:

Thanks Nils,

Thanks Gerald,
I got the problem. Do you think that welding the rectangle structure members together will help eliminate this problem? I have to say that the square tubes were quite fit to the angles and bolting them was actually a bit hard.

Nader, I would rather not discuss that further. I am trying very hard to concentrate on the MechMate design only.

Dear Gerald

Take it easy SIR, Don't worry about your MechMate design, even you got more questions or 10,000 photographs. Since June 2007, I know what is the Real MechMate Design. And i hopefully everyone also.

Thank you very much for your hard work on the MechMate.

Nobody, will change my mind " Gerald D is my hero"

I not worried about the MM design (and it is NOT perfect), I am only worried about what will happen to my free time and this forum if I start discussing other designs.

I personally agree with Gerald. If I were in his place my answer would be the same. It is not fair to introduce various designs and ask him to comment. Gerald was very considerate to note a fault in my machine. I myself, have to improve it with my mindset on my own design (which somehow I did).

Details of X axis echain: after the echain a sheet metal duct is installed. A perforated plate has been devised to carry one end of the flexible cable hose.
Attachment 7494

Spindle and its mounting plate installed.
Attachment 7495

Starting the electrical
 

The cables I use. From top to bottom:
Common ground signals cable (except for the motors), i.e. Estop signal (pin10), Pause, Resume, Zset, Home X1,X2,Y,Z,B and GND.
Spindle cable.
Motors cables.
Microswitches routing and Limit Switches/Estop 12VAC cables.
Attachment 7496

I started with the cabling of the machine, soon to notice I have to clear up the matter of the control panel, regarding its entries and exits. So I left the cabling and will attend to that after completing the panel.

As you may have noticed, there are no free walls inside this workshop in order to hang the control panel. Also I might be moving this machine to another workshop. So some flexibility should be considered and I have to make a portable one.

Ordered a 500x700x220 mm control panel. Upon collecting it, I noticed he made a mistake and made it to 500x800x220 mm. He gave me a discount to the initial price for his error. All for the better! Now I can install the VFD inside the box.

These are the panel and the support structure.
Attachment 7497

Here are the sequences for its preparation.

The first step was to locate various components inside the box with minimum voltage interference, considering the routes for the cables, interfacing connectors and input/output devices, and also their location outside the panel walls and door. Also the path of the cooling air to the VFD, the drivers and the transformer should be considered. Metallic plates might be even necessary to channel the air flow to the desired path. I tried different layouts and this was chosen:
Attachment 7498

The next step was to mark the location of the ducts and other components, inside the box.
Next I measured different components dimensions and draw and printed them on paper. Glued them on each panel surface, center pinned and drilled them. Holes larger than 16 mm were cut by hole saw. Sizes: 19, 22, 25 and 43 mm are usually the most common for preparing a panel. For 120 mm fan a 114 mm hole saw should be used. All cuts were done by hand drill.
Attachment 7499

All holes were deburred both from inside and outside, as this is really crucial. This is one side completed:
Attachment 7500

Two rectangular openings should be made. 1- for VFD’s mini keyboard. 2- for the parallel ports.
Here is my method for making rectangular opening on the control panel.
Cutting is done with the remainder of the cutting disks used for cutting the rails. These depleted disks have reduced diameter and work better in short distances. A diagonal cut helps to separate each tab easily. The rest will be finished by filing.
Attachment 7501

Attachment 7502

This is the double LPT port interface:
Attachment 7503

Here are the views of the completed bare box.
Attachment 7504

Attachment 7505

The transformer is quite heavy and will be backed by this U channel. The angle will support the other end of the flexible cable hose. Therefore, for moving the machine, the only tasks to be done are to disconnect the connectors, the earth wire and this angle iron. Then the control panel can be moved independently.
Attachment 7506

The auto air filter and its assembly components. Two off will be installed. One just above the VFD and the other one to provide air for the drivers.
Attachment 7507

Wiring diagram update
 

The following changes have been reflected in the new diagram:
Some errative colour coded wires are corrected.
The preliminary wiring of the VFD and the 0-10V board are added.
Another Estop switch added on the panel.
There amy be other revisions.

For DELTA type-E VFD the following programs are to be done:
MI1 -- 02.01 = 2 (external terminal, keypad start/stop disabled)
MI3 -- 04.05 = 8 (operation command selector = external terminal)
MI4 -- 04.06 = 19 (operation command selector = keypad)
MI5 -- 04.07 = 22 (source of second frequency command)
DCM -- 02.09 = 4 (source of 2nd frequency command = digital keypad potentiometer)

Also.

AVI -- 02.00 = 1 (source of 1st master frequency)

The attached file is a zipped .dxf file

Attachment 7536

Wiring of the control panel
 

Here will be the stages of wiring the control panel as I progress.

Prior to starting, the box was vacuum cleaned and cleaned with a damp cloth. No traces of drilling chips.
Placing and securing the cable ducts inside the panel:
Attachment 7537

These are the consumables normally used for wiring.
Attachment 7538

The wiring operation will be divided into 4 stages:
The 220VAC stage, the VFD stage, the drivers stage and the breakout and interface stage.

The 220 VAC wiring stage:
The relay and terminal blocks mounted on the DIN rail and tag numbered. Please note the spacer under the rail for ease of wiring (idea from Gerald).
Attachment 7539

All other components related to this stage are mounted in their respective places.
Attachment 7540

This is the space I made myself to start with the wiring.
Attachment 7541

The 220VAC stage completed. All wires tagged according to the drawing:
Attachment 7542

Mounting the VFD and connecting the feed wires. Mounting the transformers:
Attachment 7543

Attachment 7544

Fastening the transformer from behind.
Attachment 7545

Mounting the 39VDC module:
Attachment 7546

thats actually good organized work - I am so ashamed :(