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Messages - zafarsalam

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131
Build Thread (Update)

The bearing block at the far end of ball screw was too close to the table bottom. It's clearance is increased from 0.5mm to 3.0mm with this portable mill. Khalid has many cool tools and gadgets up his sleave.


132
Works in progress / Re: 4 axis screens for 800x600 display
« on: February 07, 2013, 08:56:00 PM »
Zafar,thank you very much ! it was my mistake. All greate! But I think here is absent the "Settings" screen,because it is very usefull . Is it possible to add it ?

It is very old project and I lost the Realdraw files for it's screen design in a hard disk crash. I am afraid you'll have to bear with what it is.

133
Works in progress / Re: 4 axis screens for 800x600 display
« on: February 06, 2013, 09:17:24 PM »
Hi  Zafar ! I really liked your screen set for 800x600 ! I have some tablet with 8" screen 800x600 . But , what happend on my tablet is this
Any advice ?

It can't read the LED images in the bitmaps folder. Make sure you have copied the contents of the bitmaps folder to the tablet.

Zafar

134
Build Thread (Update)

Here are recent photos of the machine. Khalid has tidied up the lubrication lines and also painted the foundation base a nice yellow and black striped pattern. They are also working on a platform around the machine for the operator. I'll have many pleasant surprises waiting for me when I get there.


135
Build Thread (Update)

Work is still in progress on the slide guards for the Y-axis. I am supposed to get them this evening or tomorrow. I'll have to make some fittings for them at my workshop in Karachi and then take them with me to Sadiqabad by the end of this week.

Meanwhile Khalid has installed a support for the Y-axis ball screw. The screw was almost 100 kg in weight and there was a noticeable sag when the slide reaches it's extreme end. By putting the teflon support under the unsupported length this sag is reduced by a great amount. I'll check the backlash and motor load once again when I get there.

That's it for now. More updates next week.


136
Show"N"Tell ( Your Machines) / Re: Khadgar's DIY CNC machine
« on: January 29, 2013, 09:56:10 AM »
Nice design. Building it from Aluminium? I would have made the gantry columns a little bit wider. But that will reduce your travel on x-axis and also increase it's weight.

137
Build Thread

It is Sunday and we are going to do drill tests today. It is going to be our last day in Sadiqabad (hopefully :) ). It will be our third Sunday here and Khalid has been with us all those week-ends.

Khalid has modified the post processor for Visual Mill and has put in extra M-codes for locking and unlocking the drill head during each drill cycle. He makes a sample program and we are ready to go. Put a center drill in the drill chuck, center the work piece, adjust height of tool and we press the start button. Works smoothly and finishes the cycle. Now put in a 20mm drill, edit the drill depth and run it again. Within half an hour we are through with the drilling.

The coolant pump is in operation too but the coolant drain system is not finished yet. So we apply a little amount of coolant manually for this operation. Measured the holes, inspected the drilled hole finish, noted down the speeds and feeds. Every thing is perfect.

Last few hours are spent in putting on different indicators on the machine. We leave Sadiaqabad at night and by next morning we are in Karachi. Right on time for my daughter's birthday :).

Guards for the Y-axis slide ways and the ball screw are in fabrication shop. I have to go to Sadiqabad again next week to look after the installation of guards and also discuss a few more accessories for this machine. More photos and vids to follow that visit.

https://www.facebook.com/photo.php?v=4613441528770

138
Hi Zafar,
 Looking Great!
  I'm curious about the drill radial arm.  Will there be times when light use will make clamping of the support unneeded?  Originally, the drill did not use the support arm. Otherwise(heh), has the company yet contracted you to install your newfangled auto-clamping system so that this machine operation will be carried out at the control panel?
On my little bridgemill I also installed a microswitch at the spider handle on the bridge support.  It rides on the flange of the tightening screw and allows adjustment only when the spider/screw clamp is loose.  I thought of maybe adding a motor with gear/belt reduction(high torque) to replace the manual clamping screw. 
Yours would obviously require a much more complex system for auto-clamping...and be way over budget considerations. :)

John,

In my opinion the end-support is redundant at this point. We simply put it there because it was included in the contract.

Initially it was put in design to keep both the axes perpendicular to each other after unlocking. But now we have put the lock permanent on the arm rotation so it is not needed any more. There are a lot of improvements possible to this system. One is the use of a pressure arm on the work piece to keep the stacked sheets in place. The customer is interested in putting one with this system too. Seems like a few more months of hard work are in line for us :).

139
Build Thread

Next morning we test moving our bed again. First we check the deflection on the ball nut mounting. It's not noticeable on the dial indicator. The deflection on bearing blocks is also less than before. We load the bed again and give it a trial. This time all the things work perfect. It's almost lunch time and we decide to put up the end-support column after lunch and finish it by evening. We'll do the drill test runs the next day.

The end-support column is back from the paint shop after lunch. Two days earlier we had drilled and put in the anchor wedge bolts for it's base plate. It was installed, levelled and then sealed with grout the next day. We can bolt up the end-support to it today. We hoist it up and put it on the bolt holes on the base plate. The mounting holes on both plates are out a little. Move the end support to the horizontal boring mill and slot the holes a little. Put it back on the base plate and it fits perfectly.

Now there's another problem. What will happen when someone presses the switch to move the radial arm up or down. With it securely bolted to the end-support, any up or down movement will stress both the radial arm and the end-support. We need some safety which will prevent the movement of radial arm when the bolts on end-support are tight.

After discussing some options it was decided to put a couple of micro switches on the end of bolts which secure the radial arm against end-support shaft. The switches will cut off the power to the drive motor which moves the arm. The power is restored only when both the switches are free from the bolts. With these switches installed and connected them to the control panel wiring we test their operation. It's a success. We call it a day and plan to do actual drilling the next day.

140
Build Thread

Finall we reach the day when we have to test out machine with load on it. First we check the diagonal mesurements on the bed with a sqaure drill pattern. Clamp an acrylic sheet on bed and drill 4 holes on a 1000 mm square. Get 2 m Vernier Callipers to measure the diagonals and these are within 0.04 mm of each other. Goal achieved.

Now we shift the loads from the cranes yard to the shop and put them on the machine bed one by one. It's now roughly 2.5 tons loaded onto it. We jog the Y axis again and check the torque on motor drive. It's 60% on start and stop, 40% on continuous run at full rapids. So far so good. Hook up the linear scale again and we spot a trouble. The repeatability is out by a lot and the backlash is changing with each run.

It's panic time ... Ok, let's be calm. Check the system closely and try to find out the weak points. We check the deflection on bearing blocks. It is slightly increased than before. Tightened the bolts some more and it is back to where it was. But still the problem is there. Now check the ball nut mounting on the table. This is giving us a huge deflection. The ball nut mount contraption which we used earlier is proving to be too flimsy. Tried to tighten the bolts on it and ended up breaking one up in the middle. It is decided to remove the nut locating plate altogether and drill bigger holes for the dowell pins to fix the nut with the table.

A magnetic base drill is arranged. Put on the machine table and work begins on it. We worked from 8 am till 10 pm that day. And by the end of day we had done all the machining to fix the ball nut. We will come again tomorrow morning and install the nut and test the machine once more under load. Lost my camera that day. Rest of the photos were taken by Khalid's camera. I foresee another two to three days work. I wonder if i can make it back before my daughter's birthday.

https://www.facebook.com/photo.php?v=4633322225775


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