[djbird3]

Everything I have ever read about step or direction pulse length in Mach 3 is to try 0 first, if it doesnt work lengthen the pulse time til it does work. Go in increments of 1.

It doesn't hurt anything to use a longer rather than shorter step pulse, in fact your much better off with a longer duration. In most cases the default works fine but some drivers use optocouplers that have a slow rise time in which case you may get no response or irratic stepping because of the short duration of the pulse. In my opinion the pulse duration setting is unnecessary and only complicates things for those less knowledgeable. The default duration should be 5 which would ensure any driver used would work correctly.

~Don~

[djbird3]

Is that Z limit built of Delrin/Acetal? Nice work regardless.

I'm not really sure what type of plastic it is, I thought it was delrin but it is softer and doesn't deburr very well. It might be a type of nylon but i'm not sure. Generally I use delring because you can cut it at high speeds and it cuts very cleanly, thats what I would recommend anyway.

~Don~

[LatheMaster]

I'm not really sure what type of plastic it is, I thought it was delrin but it is softer and doesn't deburr very well. It might be a type of nylon but i'm not sure. Generally I use delring because you can cut it at high speeds and it cuts very cleanly, thats what I would recommend anyway.

~Don~

Hey Don , I used to do a lot of work on plastics , X-acto was the tool of choice no matter what the material was . A brand new one that is . I used to take the X-acto's when they were deburing teflon cause you have to have a very sharp one and they threw good blades away . I'm set for life .

I just did the home switches on my machine . Once you can establish a home position on each axis you can set the soft limits and never have to touch them again . I found if you leave the soft limit switched on you can trial run the program offline to make sure it doesn't alarm out . You can also tell it how close to the soft limits you want the feed rate to slow down at . Cool software .

I like your plastic cover . Can I plagerize that one ?

[djbird3]

Hey Don , I used to do a lot of work on plastics , X-acto was the tool of choice no matter what the material was . A brand new one that is . I used to take the X-acto's when they were deburing teflon cause you have to have a very sharp one and they threw good blades away . I'm set for life .

I just did the home switches on my machine . Once you can establish a home position on each axis you can set the soft limits and never have to touch them again . I found if you leave the soft limit switched on you can trial run the program offline to make sure it doesn't alarm out . You can also tell it how close to the soft limits you want the feed rate to slow down at . Cool software .

I like your plastic cover . Can I plagerize that one ?

The limit switches are just a back-up to the soft limits not a necessity. Mach 3 is buggy and occassionally screws-up which is why I'm putting them. The lower Z axis switch is particularly usefull because it's easily adjusted. If you want I'll post a diagram for the switch mount and cover.

~Don~

[djbird3]

I spent most of today figuring out how to mount the rubber shield/guard on the Y axis in such a way that it would not interfere with the limit switches or saddle travel. After looking around my shop a while I found some 3/4" aluminum angle which I decided to use to remount the rubber. The rear mount was no problem but the front was a little tricky because of the motor mount. After a little fanageling I managed to workout a way that the rubber wouldn't get jammed between the saddle and the mount as shown below. I should have everything back together in a couple of days and I'll start focusing on the control end.
~Don~

[doorknob]

A question about your X- and Y-axis motor mounts:

I may have missed a description in the text - I see that you have made a pair of solid, L-shaped mounts for each motor. Are the mounting holes for each motor to the brackets tapped (on each end), or are they drilled to clear the mounting bolts all the way through, with counterbored sections for nuts on the opposite mounting surface (either on the short L part, or on the bearing mount that is bolted to the table)?

It looks like a very solid way to mount the motors (as compared to using four standoff sections of solid rod per motor, one for each mounting screw).

[djbird3]

A question about your X- and Y-axis motor mounts:

I may have missed a description in the text - I see that you have made a pair of solid, L-shaped mounts for each motor. Are the mounting holes for each motor to the brackets tapped (on each end), or are they drilled to clear the mounting bolts all the way through, with counterbored sections for nuts on the opposite mounting surface (either on the short L part, or on the bearing mount that is bolted to the table)?

It looks like a very solid way to mount the motors (as compared to using four standoff sections of solid rod per motor, one for each mounting screw).

All of the mounts are the same basic design, motor end drilled about 5/8" deep and tapped 10-24 and the opposite end drilled the same depth and tapped 8-32 to accomodate the counersunk flat head screws that attach them to the mount plate. This method has a few advantages over the standoff method commonly used; more rigid, lower parts count, and a often overlooked feature which is, better heat transfer. The more surface area contacting the motor means it will sink more heat and help keep the motor cooler. Steppers are designed to withstand high temps for long periods of time but the rotor field strength does weaken as a result of repeated heating and cooling which eventually renders the motor useless. So it's not a bad idea to do what you can to help keep them cool, as they say a once of prevention is worth a pound of cure.
~Don~

[djbird3]

I was playing around last night with the mill and decided just for kicks to see just how fast I could get the X and Y axises moving. I kicked Machs kernal speed up to 100k, set the inches/sec. to the max speed possible (600"/min.) @ 10000 steps/rev. The driver was set for 3.2A peak and the supply voltage 45V. The motors on the X/Y axises are Keling KL23H276-30-8A 282 0z-in steppers. I was able to zip both axises back and forth at 600"/min. with no problem, I think it's capable of even faster rapids. I decided to stop at this point before something got broke. I still haven't done any testing as far as positioning accuracy goes, this of course is the most important issue. I'll be getting around to that as soon as I get a few other small issues done. If I can get the kind of accuracy/resolution I want (approx. .0002+-20%/step) I'll stick with the 282 oz-in, if not I'll bump up to the 381 oz-in (KL23H2100-35-4B) which offers the next best torque/inductance ratio. We'll see...
~Don~

[djbird3]

Ok it's time for another installment, this time the subject will be on correcting problems with the adjustment gibs. I chose this subject because many others as well as myself have had problems with the gib adjustments on these chinese machines. There are only two basic methods used on these machines that I'm aware of employed to adjust the gibs. The first utilizes dowl pins that are beveled on one end to match the angle of the gib. The dowls are followed by a set screw that pushes them against the gib. Usually there is at least one slot cut into the gib which one of the dowl pins engage to prevent the gib from sliding back and forth. One problem that I've encountered with this method is that the dowl pins they used were to small so the gib would move back and forth causing the gib movement in one direction to be tighter than in the other, ie. it was acting like a brake in one diection because of the resulting geometry. The solution was simple, I just made larger diameter dowls that precisely fit the holes and it solved the problem.

The next method used which seems to be the most common is the drilling of small dimples into the face of the gib which the end of the gib adjustment screws engage to hold the gib in place. This is the method used on the SX2 and X2. The biggest problem with this method is that the dimples seldom line-up properly with the adjustment screws causing problems with gib adjustment. This problem can probably be attributed to the sloppy tolerances that the holes are drilled to on the machines as well as the tolerence of the jig that is probably used for drilling the dimples into the face of the gibs. For example, the Y axis gib on my SX2 was so bad that only 2 of the dimples lined up properly. As a result the gib was impossible to adjust properly, it was either too loose or would jam.

So, what to do? Well, the only thing that can be done is to redrill the dimples so that they properly align. My first idea was to try and redrill the gib with my mill but because of the difficulty in holding the gib as well as locating the drill points I quickly abandoned the idea. My next idea was to drill the gib in place to ensure proper alignment and eliminate the difficulties involved with holding the gib. First, I had to make a drill jig/bushing that could be screwed into the adjustment holes to position and support the drill bit that would be used. I did this by taking a screw of the same thread and diameter (M6x1.0mm) as the adjustment screws, approximately 20mm long and drilled the center out then reamed to 5/32" to accomidate a 5/32" drill bit as shown below. As an example the the pics below show the correction that was perfomed on the spindle gib of my SX2. As you can see in the first pic the gib sticks out by about 3/16" which robs that much travel to the top of the column. Also in the 2nd pic you can see the shallow dimples that are typical.

The procedure I used to redrill the gib was first to properly align the gib in the spindle then lock it in place using a couple of adjustment screws. Next I firmly screwed the jig into the hole that was used for the gib lock ensuring it was tight against the gib. I then proceeded to slowly drill into the gib in small increments, each time removing the gib and checking the depth of the dimple. The depth should be just enough to fully engage the end of the adjustment screw but shallow enough so that the threaded portion of the screw doesn't contact the gib. Another thing I suggest is to chamfer the adjustment screws as shown below. This helps them better engage the dimples drilled in the gib. Once I reached the right depth on the first dimple I reassembled the gib into the spindle and marked the depth of the drill bit by wrapping masking tape around it even with the end of the jig. I them proceeded to drill the remaining points to the depth indicated by the tape on the bit. A drill bit stop collar would be better but life is short and I didn't feel like making one so I used tape. The resulting outcome is shown in the last pic by the dimples that are closest to the center. Now the gib aligns properly and is easier to adjust. Next I will discuss lapping of the ways, this goes hand and hand with correcting gib problems and is a necessity if you want the best performance from your machine.

~Don~

[rewster]

nice solution on the baffle, I've been pondering the same problem since my y-axis extension. thanks for sharing.

[ClintHarwood]

Hey djbird3

thanks so much for sharing... How far have you gotten with that spindle speed control? I too have an SX2 and have cnc'd it, modded for more y and Z travel and stiffened coloumn... NOw I want to CNC spindle but not sure if the digispeed will do the trick since this is a different control board than the X2. This one controls a brushless motor which is quite different. I wonder if the pot works the same as the brushed X2? If you can figure it out please let us know. I'm planning on ripping my beast apart and spending some quality time with a voltmeter in my lounge

Your help is totally appreciated!
P.S. I used Hoss's plans for my conversion.... Look into getting bigger balls for your ball screws and also make sure you make your gibs and table real smooth so you can tighten the gibs nice and tight. relaly helps with backlash and a nice smooth cut.

[djbird3]

Hey djbird3

thanks so much for sharing... How far have you gotten with that spindle speed control? I too have an SX2 and have cnc'd it, modded for more y and Z travel and stiffened coloumn... NOw I want to CNC spindle but not sure if the digispeed will do the trick since this is a different control board than the X2. This one controls a brushless motor which is quite different. I wonder if the pot works the same as the brushed X2? If you can figure it out please let us know. I'm planning on ripping my beast apart and spending some quality time with a voltmeter in my lounge

Your help is totally appreciated!
P.S. I used Hoss's plans for my conversion.... Look into getting bigger balls for your ball screws and also make sure you make your gibs and table real smooth so you can tighten the gibs nice and tight. relaly helps with backlash and a nice smooth cut.

Hey,

The digispeed will work on the brushless controller with no problem. The pot on the brushless controller provides a 0 - 5 Volt signal to the microprocessor on the controller board which is used to set the speed. I intend on using closed loop spindle control and the only problem I foresee is the amount of lag between the time the control voltage changes and the time it takes for the spindle to catch up with this brushless controller. At the moment I'm dead in the water as far as the spindle goes because I had to send it to John Gerling for repair. The controller had a problem from day one so this will be a warranty repair. When I get it back I'll probably do a thread on modifying it for closed loop control.

As far as my mini-mill is concerned I've got everything done but the spindle. I lapped the ways of all three axises and have managed to get them very smooth. I can tighten the gibs to the point where I can measure no side movement on the table and still get 600"/min. on rapids at very high acceleration rates with no problems. The ballnuts I'm using are the REX zero backlash nuts so bigger balls aren't necessary. So far I can only measure about .0013 backlash on the table, not exactly zero but should be good enough. At the moment I'm working on a set of clamp type oldham couplers for all three axises. Probably by the time I get the controller back I'll have all the little stuff done and I'll focus on spindle control.

~Don~

[djbird3]

By request here are a couple of pics and diagrams of the Z axis motor mount. Eventually I will post the complete plan set when I get around to editing and fully annotating all my diagrams.
~Don~

[poopy_pants]

Thanks Don!! :cheers:

[gopher]

have you figured out the lapping procedure

Sent from my GT-P1000 using Tapatalk

[poopy_pants]

ClintH -
What are you using for a Stepper Drive? I run mine from the VFD output on the G540. Used this as a guide G540 VFD

Hey djbird3

thanks so much for sharing... How far have you gotten with that spindle speed control? I too have an SX2 and have cnc'd it, modded for more y and Z travel and stiffened coloumn... NOw I want to CNC spindle but not sure if the digispeed will do the trick since this is a different control board than the X2. This one controls a brushless motor which is quite different. I wonder if the pot works the same as the brushed X2? If you can figure it out please let us know. I'm planning on ripping my beast apart and spending some quality time with a voltmeter in my lounge

Your help is totally appreciated!
P.S. I used Hoss's plans for my conversion.... Look into getting bigger balls for your ball screws and also make sure you make your gibs and table real smooth so you can tighten the gibs nice and tight. relaly helps with backlash and a nice smooth cut.

[djbird3]

have you figured out the lapping procedure

Sent from my GT-P1000 using Tapatalk

Yeah I've got a procedure but just haven't gotten around to putting together a post, I've been busy with other stuff. I'm going to get around to it probably by the weekend. I still have a lot of things yet to cover in this thread so stay tuned.

~Don~

[djbird3]

Since I don't have a functioning spindle yet I've been working on other stuff. One of the things I've done is made a set of clamp type Oldham couplers for all 3 axises. These are fairly easy to make and work really well. They're zero backlash and should last for years on a X2 or X3. Clamp type couplers are far superior to the set screw type because they don't get loose and don't mar your shafts. Anyway, I've provided a diagram of the part if you want to make a set. I'm probably going to shorten these by about .050" in a future revision because they were a rather close fit in my motor mounts.

~Don~

[Roccobro]

Any plans or thoughts on an automatic oiler? Is there a need?

Thanks for sharing Don.

Justin

[mrcodewiz]

Those are some nice looking oldhams, Don.