Homing and limit switch

[shadowless]

Hi,
Read abt the homing and limit switches in the Mach3 configuration pdf but not sure exactly how to set it up on the Taig Mill.

Wonder where do you guys mount the homing and limit switches for the Taig mill? I can't quite figure out.

What type of switch should i get that would work well as a homing switch?

Best Regards

[macdarren]

I just went through this with my Taig.

I will describe how and where I mounted mine but I'll try to post some pictures soon.

First off my general feeling is that I don't like to drill holes or other wise modify my machine, at least not until I am certain what I am doing will work as expected.
I also prefer my switches to be stationary. I used the same sealed lever roller switches in all positions. I used 1/8 Alum plate and angle for all the brackets.

I installed my X limit/home switch in on the frame where that little center post is located...I just unscrewed the retaining bolt and pulled the post as it serves no real
good purpose. I then built an L shaped bracket that is retained by using a 10-32 bolt into the original retaining bolt hole. My eventual plan will be to make a bracket the mounts in the hole where the original post was but I haven't gotten to that yet. With the switch located in the center I then created 2 ramps that I mounted to the front of the X table in the slot that runs the length of the edge of the table.

For the Y movements I used two switches one mounted in front using another bracket that bolts to the black Aluminum plate that retains the lead screw....for this I just used the original retaining bolts and cut my bracket to clear the lead screw and mounted it on the outside. As the table runs out from the column is runs over the roller switch to trip the limit. In back I made another plate that I drilled with a 1/2 inch hole an slipped over the big bolt that holds the column in place then put another nut on that bolt...the bolt was plenty long to do this but it means a bit more effort when tramming the mill. To this plate I mounted another small piece of angle with a that carries the switch and holds it in position so when the table comes back it again slides over the roller and trips the switch. I may try a couple of thinner jam nuts in the future and see if I can get it so I can tram the mill without removing the plate but it is not a big deal either way.

Lastly I placed the Z switch at the top of the mill retained again but the two screws that hold the the mounting bracket for the motor. In this case I replaced the original screws with ones that were 1/2 inch longer so that when tight the protrude out the back of the mill enough to mount the switch plate and put on a couple of nuts. this plate holds the switch so that the carrier for the head stock closes the switch just before the mill reaches the top of it's movement. This is the one switch I have a slight problem with as if I push the motor past the switch point it will jam the switch in a limit exceeded position but then you should not do that and it fails in the tripped position.

I haven't found a good or meaning full way to mount a lower Z limit. I am not sure it will really mean anything unless you have a certain maximum tool length. It is however in some ways the most important switch as it is the one that would prevent you from running the mill into the table or preventing the head stock from dropping totally off the lead scew (I am not sure about if that actually happening) but when something went haywire with my controller/positioning I did cut a nice divot in the table.

[rowbare]

Here is a really nice Taig limit switch setup

http://www.finelinehair.com/home/E-S...20switches.htm

[shadowless]

Hope to see photos of your setup. At the moment, I don't like to drill unless really necessary.

That finelinehair setup is nice. But seems like a lot of milling and drilling. Can make the mill parts at the moment.

[macdarren]

Here is a link to some marginal photos of my limit/home switch setup.

http://gallery.me.com/macdarren#100019

[shadowless]

My switches finally arrived today and i figure out the simplest way to mount them with just pieces of L-plate cut from one piece of aluminium section. All the drilling are done on the mounting plate and just bolted on with 10-32 stainless steel screws.

Post the pics later.

[Mini Beast]

Is anyone else running their machine without these switches? I'm going to set up my Taig in the next couple of weeks, and I wasn't planning to use them (at least at first). The only one I will have is the e-stop.

[Hirudin]

I'm not using any... in fact I've only recently started using the 'soft limits' that can be set in Mach3.

So far I haven't left my machine running unattended though. Once I do I will probably want to get some real limits.

[shadowless]

Think it is a small price to pay for the peace of mind. But definitely you can run without it. E-stop definitely useful, i used that a couple of times while setting up the limit switch and soft limits.

[macdarren]

I ran mine for a short time without the limit switches and I have to say were I to do it again I would not. At the very least you will want to use a tool plate to protect the table. I found while I was first getting things going I had several problems that led to run away. I was pretty careful and tried to keep the work raised off the table some to give me a chance to stop the mill if needed and used some cheap AL plate to protect the table most of the time. I did manage to estop several times when things when wrong, before I drove a 3/8 mill into the table during a rapid reposition where the machine somehow lost it's Z reference.....I then decided it was time to get some limits installed.

[Hirudin]

Originally Posted by macdarren I ran mine for a short time without the limit switches and I have to say were I to do it again I would not. At the very least you will want to use a tool plate to protect the table. I found while I was first getting things going I had several problems that led to run away. I was pretty careful and tried to keep the work raised off the table some to give me a chance to stop the mill if needed and used some cheap AL plate to protect the table most of the time. I did manage to estop several times when things when wrong, before I drove a 3/8 mill into the table during a rapid reposition where the machine somehow lost it's Z reference.....I then decided it was time to get some limits installed.

Can a limit switch prevent the Z from going too low? It seems like it would only work if all your tools were the same length.

[macdarren]

you are right there about the Z but the limits help in two ways.

First you can have your machine home to the upper switch which just means that at least it knows where it is at the start of a run (that is what got me).

But my thinking is I now use a thick tool plate or my rotary table and I set the lower limit so that the longer tools still can't cut down past the plate.

Currently the longer tools will cut into the plate but not all the way through unless I run something really long. Obviously it is not a fool proof system and my playing the fool will probably still manage to mess up again but I think it 'safer' than before. Ultimately I want to use some sort of tooling setup that better controls the tool length.