Emco PC120 Turn

[jamesgates1000]

Hi, does your lathe have a Baruffaldi TOE80 turret like on a denford cyclone?

http://www.1stmachinery.com/Resource.../1008_6790.JPG

Is so I have a few spare blocks and boring bar sleeves that i made up and also some spare ER25 and ER16 Holders that I bought and modified to suit the 25mm tool holder if you are interested

[Chaz]

Hi, does your lathe have a Baruffaldi TOE80 turret like on a denford cyclone?

http://www.1stmachinery.com/Resource.../1008_6790.JPG

Is so I have a few spare blocks and boring bar sleeves that i made up and also some spare ER25 and ER16 Holders that I bought and modified to suit the 25mm tool holder if you are interested

Nope, similar but not as 'angular' as that. Ill take some pics.

[Chaz]

Please talk to me about Mach 3 tool ofsets.

Mine work however I am confused about one aspect.

This video https://www.youtube.com/watch?v=IAY6M4Q7fIE shows that a Master Tool is set at zero (against an arbitary plane, defined by a bar in the chuck) and all others tools are set against this. I understand this principle, its the way I use my mill offsets.

However, what I am not sure about is how to ensure that the machine 'knows' where X is say 0 or 10mm from the centre line.

The way I have done mine is to home my machine and set all tools from this point. My DRO will therefore say '20mm' and give me a 20mm stock if I cut along that plane (both diameter mode).

The problem is that the limit switches do not repeat 100% and whilst its reasonably accurate, I am not 100% getting the same diameters once the machine is rehomed.

I could use some form of a dialguage and reference of this (for X). Thoughts?

The other option is to home the machine once, then never again. Instead of homing it I should use G Code to 'go to home' but not use the limit switch. Assuming the machine is powered down and restarted with the turret in this location, it should repeat however as I use steppers (not servo), this is not perfect. Any replacement of a tool / tool tip or need to rehome means that my 'diameters' are no longer 100%.

I find that then resetting the diameter size (John Saunders does similar) needs you to cut a part manually, then measure it and then do some sums to get the offset correct. I find this tedious and long winded. Is there a better way?

Thanks

[m_c]

Take test cut with known tool, don't move X after taking cut, measure cut, and enter value into X DRO.

Provided you're not doing anything that affects tool offsets into relation to each other, then you don't have to touch individual tool offsets. All you have to do is establish the actual X axis position.

However, install a decent homing switch on the X axis. On a lathe, it makes life so much easier.

[Chaz]

Take test cut with known tool, don't move X after taking cut, measure cut, and enter value into X DRO.

Provided you're not doing anything that affects tool offsets into relation to each other, then you don't have to touch individual tool offsets. All you have to do is establish the actual X axis position.

However, install a decent homing switch on the X axis. On a lathe, it makes life so much easier.

Thanks. The pain here is to do a test cut .... I think you use the lower DRO here for the 'new' measurement?

The homing switches look to be 'decent'. They are proximity ones. I'm not sure what the repeatability is with them. Ill do some testing over the weekend. How much 'tolerance' should I expect with homing? Better than 0.01mm?

[m_c]

What lower DRO?
From memory, you just enter the measured value into the main X axis DRO.

Homing accuracy depends on how accurate your parts/machine are. On my first lathe, I had an opto slot sensor that I couldn't measure any noticeable change with using a 0.01mm graduation DTI.

[Chaz]

What lower DRO?
From memory, you just enter the measured value into the main X axis DRO.

Homing accuracy depends on how accurate your parts/machine are. On my first lathe, I had an opto slot sensor that I couldn't measure any noticeable change with using a 0.01mm graduation DTI.

Sorry, on one of the videos the guy uses the tooloffset screen. I think he edits the lower DRO to get it to be the same as the measured diameter. In my case I was manually subtracting (or adding) to work out the required difference to make the reading correct. In the tooloffset screen I dont think you can edit the top DRO. Perhaps I'm just doing it in the wrong place.

Ill use a dial gauge on the weekend and test repeatability.

[m_c]

Don't bother with the tool offset screen. Just take a test cut using one of the main screens, then measure and enter the value into the main DRO.

[Chaz]

Don't bother with the tool offset screen. Just take a test cut using one of the main screens, then measure and enter the value into the main DRO.

Thanks, that removes one of the pain in the ass with sorting this problems as I have to go from screen to screen continuously.

So if my switch is not repeatable, ill set the offsets from the master tool (and use the cut / measure / input method). If it is, ill set it up from the switch.

[Chaz]

Ive ended up setting offsets the painful way from the homing switch, seems to work better for me. Will test again today and see if its still working.