Author Topic: DRO for Warco Major mill (Read 38793 times)

PekkaNF · « **Reply #25 on:** January 07, 2019, 04:09:20 PM »

Checked this option at the far side of the table and there is a loss of travel or loss of measurement.

If the read head is put side of the pilar, it does not interfere with Y-axis travel, but does not read extreme right of X-axis direction.

If the read head is located to read all of X-axis travel, it will clip about 9 mm of Y-axis travel, does not sound much, but it is all located at the useful front part of the table.

So, did a mock up all three options and measured how much things change. No really easy and smart way to do it without any compromise.

Pekka

PekkaNF · « **Reply #26 on:** January 09, 2019, 04:11:58 AM »

Still dragging my feets....

And got some piece of usefull information: Apparently castings of these cheap mills are not normalized! Amazing. Therefore milling them grooves or pockets is apparently a bad idea. I found one case that mill T-slot table was straight originally, but developed a warp after a pocket for ball screw nut and a grove for ball screw was milled. The warp was in order of 0,1 mm and the grove for the ball screw was 3 mm deep 30 mm wide. Therefore it looks like a bad idea to mill on cast surface. Bugger.

Plan A is to mount:

* X-axis scale behind the T-slot table and accept a 60-70 mm of lost travel distance. I very tempted to use supplied aluminium extrusion to mount the tape, it would provide some protection for the tape and inhibit only 1 mm of Y-axis movement.

* Y-axis is harder, I allready ordered the parts to mount the tape at the top of the table on flat channel - no problem there. But the read head mount would need a pocket milled right into virgin cast surface on the saddle - where it has a great potential to warp TWO axis movement.

Pekka

awemawson · « **Reply #27 on:** January 09, 2019, 05:32:28 AM »

The warping is obviously relieving stresses in the casting by removing a surface layer, in much the same way that cold rolled mild steel will warp if one side only is milled.

Sadly though if the castings are as bad as you suggest then there will be some warping over time even if not machined

It may not be appropriate in the case of your mill, but to overcome a similar space / layout issue on my Colchester Master when Newall came to fit the DRO they used an 'outrigger' to place the actual ball tube well the the rear.

RussellT · « **Reply #28 on:** January 09, 2019, 06:12:09 AM »

Rather than accept losing travel wouldn't it be better to mount the x axis DRO on the front of the table and do something else so you could continue to use stops. On my mill I added a steel rod below the x axis scale which I can clamp stops to. Although to be honest I haven't made the stops yet.

Russell

PekkaNF · « **Reply #29 on:** January 09, 2019, 07:15:59 AM »

Thank you Andrew, I know that system and lay-out. I rather use cheap standard parts to this one.

I will deal with the warping when it shows.

Quote from: RussellT on January 09, 2019, 06:12:09 AM

Rather than accept losing travel wouldn't it be better to mount the x axis DRO on the front of the table and do something else so you could continue to use stops. On my mill I added a steel rod below the x axis scale which I can clamp stops to. Although to be honest I haven't made the stops yet.

Russell

I was considering it, but it would bring the read head forward and fairly middle - to my work area.

Easiest way to mount the tape on the front of the table would be to remove the measurement tape rule out of groove and replace it with the magnetic tape. Perfect fit. Then it would be possible to use mounting holes of the stationary top block and indicator and replace it with a foot that would double as stop block and read head mount.

But then the tape would be really front of the table, where I tend to use squares, tools, magnetic stand etc. And the read head would be pretty proud and non shielded location.

Second option would be to mount the tape below the current stop into more protected position. That would mean some machining for the magnetic tape (2x10mm grove for magnetic tape + 0,5x16 mm for 0,2 mm stainless steel protective strip. This machining would be into readily machined surface .... maybe minimal chance for warping?

OR bolt on rail for magnetic tape and wonky looking arm. for stopper to clear this.

Another hour or two lego play time on the milling machine

Maybe all would just fit there and convincingly stay out of troubles way.

Pekka

PekkaNF · « **Reply #30 on:** January 09, 2019, 04:37:31 PM »

I am now considering seriously fitting the scale front/low in lieu to X-axis stops. Where is this world getting at?

Pekka

BillTodd · « **Reply #31 on:** January 09, 2019, 04:55:53 PM »

Mount the scale to the front. then...

make a couple of stops that attach to the Table dovetail and to the small area below the scale . If you are using stops , then you are unlikely to be using the full range of the table , so the loss fo a few centimetres of 'stop' range wil not cause you a big problem ( nothing that could not be fixed 'on the day')

Make an electrical stop that bleeps with incresing rapidity as you approach the stop point.

seacat · « **Reply #32 on:** January 09, 2019, 06:23:55 PM »

The term "snagging" in the UK usually refers to correcting the defects in a project. As a project progresses defects arise which need to be 'corrected'. These are put on a "Snagging List". Before the project can be said to be completed all the '"snaggs" on the list need to be corrected to the project managers satisfaction. Amongst other things.

That's the theory anyway! The practice may be different!

Chris

PekkaNF · « **Reply #33 on:** January 10, 2019, 01:32:16 AM »

Quote from: BillTodd on January 09, 2019, 04:55:53 PM

Mount the scale to the front. then...

make a couple of stops that attach to the Table dovetail and to the small area below the scale . If you are using stops , then you are unlikely to be using the full range of the table , so the loss fo a few centimetres of 'stop' range wil not cause you a big problem ( nothing that could not be fixed 'on the day')

Make an electrical stop that bleeps with incresing rapidity as you approach the stop point.

That is actually a very good idea!

I will not need them often (even less so with DRO) and mechanical stops right at guide ways must surely be most accurate. Pretty high on the list when making about hundred teeth and depth is is set by a end stop (done that). Now I need to check the details i.e. which surface to use as a stop, does it needs a taped stud or small flat or what. Would be easy to do now when it's in parts.

Pekka

PekkaNF · « **Reply #34 on:** January 10, 2019, 02:43:17 PM »

Jep, it would be pretty easy to mount the rail into table stopper rail.

Looks like should remove the tape rule from the table or least flatten the rivets.

Standard read head mountung hardware does not fit, but proper one is not too hard to make.

PekkaNF · « **Reply #35 on:** January 12, 2019, 08:52:56 AM »

And because this is somewhat disasembled, might as well check how true parts are.

I measured horisontal plane in 0,01 mm resolution, checked first with thick blue, knock off some raised edges and burrs and then checked with very thin blue.

The surface looks a litle unusual.

seadog · « **Reply #36 on:** January 12, 2019, 08:58:13 AM »

I see a scraping project about to commence

PekkaNF · « **Reply #37 on:** January 12, 2019, 09:58:56 AM »

No no no...this is good enough now. I'll use it as it is until it starts acting up. There is still a possibility that castings start to warp or something.

seadog · « **Reply #38 on:** January 12, 2019, 10:42:04 AM »

I assume that you're hoping the castings will warp in the correct directions then, Pekka?

PekkaNF · « **Reply #39 on:** January 12, 2019, 12:39:52 PM »

I hope that castings will behave themselves.

The table looks pretty straight and contact between table/saddle is pretty civilized.

I don't have dovetail straight edge to check the guide ways properly, but looks ok.

Pekka

PekkaNF · « **Reply #40 on:** January 19, 2019, 05:38:59 PM »

Today I had few extra hours and plan was max. results with minimal effort.

I could not locate thick enenough aluminium for support, I mostly used 30x30 mm 2 mm thick L-profile.

Mechanically it appears fine, but I haven't tested it yet electrically.

Magnetic tape is now 2 mm off the sensor. Plan is to file 3 mm bolt holes oval just enough to bring the tape near the sensor but avoid physical contact.

Still two separate items left: X-axis and configutation.

PekkaNF · « **Reply #41 on:** January 19, 2019, 06:57:55 PM »

Now the interesting question. Which way should axis indication increase?

CNC easy, two views, same result...

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BUT this is a manual machine

1: When I turn Y-axis wheel clockwise table will move away and numers on micrometer will increase.....it would be elegant if the numbers on DRO would increase as well.

2: Looks like it is rather popular to zero origo on fixed jaw of the vice. Obivious benefits.

Any takes?

Pekka

Will_D · « **Reply #42 on:** January 20, 2019, 04:45:34 AM »

You can configure each axis to read either positive or negative for a given movement.

awemawson · « **Reply #43 on:** January 20, 2019, 05:30:47 AM »

These are the axis designations on my Beaver Mill (Fixed table moving quill) and my Beaver Lathe (Moving Turret) if it helps:

PekkaNF · « **Reply #44 on:** January 20, 2019, 06:42:28 AM »

Forgot to put few earlier pics on cast iron flats for mounting. 16 mm indexed mill, M6 threads and 3 mm spacer washers to raise the bracket off the rough cast surface.

There should a alrge mill in the darkest corner that is big enough to mount all parts of the other machines for modifications....

Tested the Y-axis, works fine and tape/head is in correct relation (both pulse count A/B, ref and direction).

Pekka

PekkaNF · « **Reply #45 on:** January 22, 2019, 05:04:44 PM »

Two hours on two days -each and X-axis measurement is ready.

Still left final cable routting, but this looks pretty compact.

Not as well hidden than my original plan, but better than I were afraind.

I tried to make all prts to hug as close to machine core as possible.

Pekka

tom osselton · « **Reply #46 on:** January 22, 2019, 05:31:56 PM »

That is a nice way of doing it!

PekkaNF · « **Reply #47 on:** May 20, 2019, 12:35:32 PM »

This installation has been working fine.

Alternative to magnetic scales video here - glass scales:

Incidently, pretty much same locations and logic with this video and my installation.

News:

Author Topic: DRO for Warco Major mill (Read 38793 times)