Thursday 22 March 2018

How to Modify a Mach3 Screenset - episode 208

This episode is a revisit of a video I made almost 2 years about configuring my Mach3 pendant and modifying the screenset. What I didn't realize at the time was the screenset was messed up when the screenset editor opened the file. While it was subtle a viewer who was having the same problem contacted me and pointed it out. Until I saw it on my video I hadn't noticed it but now it was obvious. I tried at the time but couldn't get it to work and I still don't know why it doesn't work. Changing computers to edit the screenset seems to make thing much worse to the point that it was impossible not to notice and even more impossible to use the screenset. In my defence I don't use the 1024 screenset in my day to day machining and the editor worked well with the screenset I use. I picked on the 1024 set because it comes with Mach3 so everyone has it and in theory one screenset is as good as another. 
A few weeks ago I was helping another subscriber with a problem he was having and decided to add a digitizing LED to the screenset main page which meant I was back battling my old friend the screen editor again. This time I tried the newer version editor Screen4 and found it works well with the 1024 screenset. With the new skill learnt I thought it would be a good opportunity to update my previous video and introduce the pendant to new subscribers as I find it an indispensable addition to my machine. Especially with the modified keys on it. It is also a good opportunity to introduce the updated Mach3 Autozero script which gives added safety to the script.

Click to watch the video

The software used to edit the screenset is available from the Mach3website on this page.

Direct download link.

Buttons, images, DRO's, OEM's and much more
The Screen4 software allows you to add more than just an LED to the screnset. You can add the entire range of components needed for your screen. It is well worth taking the time to have a play and see how a screenset is made. Wile I only added with an LED the priciple is the same for all the other components. Selct the component type from the left havd column and click to add it to the page. Drag  to the required location and double click to open the properties. Enter the required changes and that is it.

List of OEM codes used in Mach3

The new Screensets
If you would like to use the new screenset you can fint them here

The New scripts
If you would like to download the new scripts with the touch test functionality you can download it here. They can be found in the Mach3 folder. Select either Metric or imperial depending on your machine and don't forget to change the plate thickness in the script.

If you are looking for a pendant similar to mine this it the current version. It has a 4th axis that mine diesn't have which you can use either for a 4th axis or another function of your choosing simply by changing the screenset  as shown.
The link will give you multiple search results so you will want to fine a pendant that looks the same as the picture below and at the best price for you.

This particular pendant is available from multiple sources such as Amazon, so it will pay to look around. The link below is an affiliate link.

Where to from here?
This will help those who wish to modify their existing screenset to add additional functionality or even make a new custom screenset for your machine. you are only limited by your imagination. 

I hope you find it useful and until next time keep those chips flying.

Saturday 10 March 2018

Lets talk about Stepper Motors - Episode 207

Stepper Motor kits abound on Ebay and unfortunately all too often they are not very good kits.
They sound great. Huge holding torques, very very reasonably priced drivers, motors and power supplies. Unfortunately most of these kits use poorly designed stepper drivers, they are feed with low voltage power supplies and the motors are a very poor match for the drivers that have the job of making them turn.
In this video I try and show the issues associated with stepper motors, why they are as they are and how to choose a well matched system. The drive system on your machine is the biggest hardware investment you will make and one of the most important. It doesn't matter how good the machine is, if your drives are rubbish so is your machine.

 Click to watch video

The biggest myth of stepper motors is that bigger is better.
While in some respects this is true, there are certain criteria that must be met. The motor, driver and power supply must compliment one another to get the best out of your motors. A small well matched system will invariably out perform a poorly matched motor / driver / power supply combination.
Stepper motors are rated in holding torque which is how much power they have when they are doing nothing. The larger they are the better they will do nothing for you.
Big stepper motors are sold to catch the buyer not run your machine. The bigger the motor the bigger it's internal losses are and the more power you require overcome these losses and drive them properly. Don't get me wrong. There is nothing wrong with a properly driven stepper motor and in many cases large motors are needed to move heavy axis. Generally though the home builder making their DIY machine does not need to exceed 400 ozin or so unless it is a big heavy machine they are building or they need it to move very fast. Medium powered motors are more common in this hobby.
The problem comes when kits sold on the likes of ebay driven by a TB6560 based driver board using a 24 volt power supply and trying to drive 425 ozin motors. The TB6560 boards were never very good to start with and many of the boards have design flaws that have been extensively discussed on the CNC Zone over the years. The voltage is way too low to drive a medium size stepper motor and many of the adverts don't even give you the basic specs of the motors.
It is vitally important to check the spec on every part of any kit being offered and make sure it is a reasonable match for the rest of the system. If it isn't or there are no specs then move on and find something else.

Additional Information

Click the link below to download the Spreadsheet for calculating Drive voltage and current requirements.

Click the link below to visit the Gecko site and read their Stepper motor guide. 

Stepper Motor Basics

My personal opinion
One thing in Geckos stepper motor guide that I disagree with is the sizing of the motors. While I am sure they are correct in their assessment, they are talking about a product you may be producing that will never change. As a hobbyist we are constantly tinkering and upgrading. In the case of purchasing a Gecko G540 I would purchase the largest motor that it could correctly run rather than one that fits my needs today. In the case of the G540 that is the 381 ozin motor I showcased in the video which if memory serves my correctly was actually specially made to compliment the G540 drive when it first came out. No matter how big a motor you put on it you will not get any more power out of it. A larger motor will give you more power at slow speed but as you try and move faster it will rapidly loose power and the 381 ozin motor will out perform it. Not only that but that little motor is capable of running a range of Joe's DIY CNC machines built up to 4 x 8 foot configuration for example. 
They will drive your small machine today and can be moved to a larger one tomorrow.

It is also important to note that Gecko are not the only makers of good drives systems on the market but the G540 is the only one that I have experience with which is why I reference this one.

4 Axis Drive kit.
I wish to point out that by using the links below I will earn a small commission on any purchase you make at no additional cost to you. It is important to note that if you purchase the individual components making up the kits from various suppliers and assembly them yourself you will save yourself money. Your responsibility is to yourself and I will be happy no matter where you purchase your drive solution from so long as they work well for you. I encourage you to look around for the best deal and solution that meets your needs. I have not personally purchased from this supplier but it is a USA based company that is selling this product.

It is important to note that this supplier does have a 3 axis kit but I would recommend asking them to price you this kit and leaving off the extra motor and 12 foot cable if you want 3 axis. Their current 3 axis kit uses a 7.3 amp power supply and if you want to add the 4th motor later you will need to upgrade the power supply to power it. Getting the 12.5 amp supply now will save later on. It never hurts to have a spare motor and cable just in case, if funds allow. Buying a 4 axis motor kit for your 3 motor machine is not crazy. When you want to add a rotary axis or have a faulty motor or cable you will have the parts you need..

With this kit you will need to supply a case or build one to house it in and a minimum of wiring is needed. If you want an Estop button you will need to purchase this separately.
The Gecko G540 has a built in Break out board to which you can add relays and limit switches. Additional wiresare added to the G540 using screw terminals so those who are not comfortable soldering need not worry.

This kit includes:
4 x 381 ozin motors
4 x 12 foot cables to the motors
1 x 6 foot parallel cable  
1 x 48 Volt 12.5 amp power supply
1 x Gecko G540 4 axis drive system
Please let me know if this link stops working or the kit no longer matches the photo above.
Use the contact link on the right.

Mushroom emergency stop switch if you want one.