Author Topic: coaxial centre finder, another method  (Read 26025 times)

Offline geoff5269

  • Full Member
  • ****
  • Posts: 152
coaxial centre finder, another method
« on: March 17, 2015, 08:20:45 PM »
I was thinking of treating myself to a coax centre finder, to one where a dial gauge with a long feeler is fixed in the chuck of a mill and a long feeler revolves around the part while the clock faces forward and you just move the table controls until the needle is still, this seemed ideal but I realised it needed a lot of head room which I would not have once I have added the rotary table and then the work. So I wondered if I could use my DTI having offset it the correct amount. I normally use my RT with a 12mm spigot fixed and then put a 12mm bar in the chuck and bring them close together until I can't feel any step, and now I can fine tune it by substituting the DTI. so I don't really need a new toy.  see pictures
Geoff

Online mklotz

  • Full Member
  • *****
  • Posts: 2620
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: coaxial centre finder, another method
« Reply #1 on: March 17, 2015, 09:21:40 PM »
You can expand on this idea by buying or making a "Zero-It" type indicator holder...

http://www.hobby-machinist.com/threads/zero-it-indicator-holder-finished.9655/
Regards, Marv
Home Shop Freeware
https://www.myvirtualnetwork.com/mklotz

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #2 on: March 17, 2015, 09:57:07 PM »
I don't yet have a RT but would it work if I mounted a MT centre in the quill of my mill and then moved it down into the socket of an unfixed RT. Once centred ithe RT could then be securely clamped. Would that work? I often use a similar method for centering items in the mill vice.

Online mklotz

  • Full Member
  • *****
  • Posts: 2620
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: coaxial centre finder, another method
« Reply #3 on: March 17, 2015, 10:45:31 PM »
I made a tapered plug to fit the tapered (MT ?) hole in the RT.  It has a hole to take a precision 1/4" pin.  Said pin has a center hole in one end.  Fitting a center finder (the conical end on a typical double-ended edge finder) into a collet in the mill and plunging it into the center hole allows the table to be centered, either by touch or by measuring across the collar on the conical end.

It's easy to make up stubs with one end turned to 1/4" to use to center workpieces on the RT.

Although the tapered plug sits below the RT table surface, it can be removed without access to the bottom of the RT if the RT is bolted down.  At the bottom of the aforementioned 1/4" hole is a smaller hole tapped 10-32.  A small slide hammer slug on the end of a long 10-32 bolt pops the slug out quickly.
Regards, Marv
Home Shop Freeware
https://www.myvirtualnetwork.com/mklotz

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3781
  • Springfield, Tennessee. USA
Re: coaxial centre finder, another method
« Reply #4 on: March 17, 2015, 10:54:05 PM »
Sorry guys, but,  this seems like a good time to ask this newbie type question;  Marv just mentioned the conical end of an edge finder,  so, when using this end do you move it where there is no "kick out" and running true  or watch for it to kick out and stop. Does that make sense?  :shrug:

Cletus

Online mklotz

  • Full Member
  • *****
  • Posts: 2620
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: coaxial centre finder, another method
« Reply #5 on: March 17, 2015, 11:21:07 PM »
Sorry guys, but,  this seems like a good time to ask this newbie type question;  Marv just mentioned the conical end of an edge finder,  so, when using this end do you move it where there is no "kick out" and running true  or watch for it to kick out and stop. Does that make sense?

I generally use it without having it rotating.

Look carefully at one.  Just above the conical section is a cylindrical section whose diameter matches the diameter of the tool's shank (often 1/2").  When the cone is centered this cylindrical section is coaxial with the centerline of the shank.

There are two ways to decide if the cone is on center.  Run your hyper-sensitive fingernail over the joint between the cylindrical section and the shank and, if you sense a tiny edge, move the cone until the joint disappears to your perception.

The other way is to measure across the joint with a mike.  When the measurement equals the shank diameter at every angle, the cone is centered.
Regards, Marv
Home Shop Freeware
https://www.myvirtualnetwork.com/mklotz

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13860
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: coaxial centre finder, another method
« Reply #6 on: March 17, 2015, 11:54:28 PM »
Marv, is that Nelson's site? I have wondered if he was still around. Seems like there were some real growing pains for a while over there but I stopped visiting it a long time ago, no criticism of the site, just wasn't my cup of tea.

Bill

Offline Hugh Currin

  • Full Member
  • ****
  • Posts: 720
  • Box Elder, SD, USA
    • www.currin.us
Re: coaxial centre finder, another method
« Reply #7 on: March 18, 2015, 01:04:28 AM »
so I don't really need a new toy.
Geoff

This seems rash and jumping to conclusions way too quickly. Of course you need a new toy, no question about it. How could you think otherwise.

I have a CoAxe indicator and find it very useful. I tend to first use it without powering the spindle. Align it to the X and note the reading. Rotate 180deg and note the new reading. Split the difference by moving the X axis. Do the same in the Y and you'll be close. Then power the spindle at slow rpm and take any wobble out of the dial.

They are not free and do take up quite a bit of headroom. Not too big a problem on my knee mill but may be on a smaller mill. They are a precision instrument so try not to drop one to the floor. But at least for the CoAxe, they are good at repairing damaged units (for a price) (at least I've heard this, I'd never be careless enough to drop mine :-)

A test indicator will work fine for the same purpose. The only down side is having to crane your neck around to see the dial face.

These have been my experiences.

Hugh
Hugh

Offline sshire

  • Full Member
  • *****
  • Posts: 3044
    • LS Editions
Re: coaxial centre finder, another method
« Reply #8 on: March 18, 2015, 01:14:32 AM »
My Blake (eBay. Slightly used but in the wooden case with a full set of probes) gets used a great deal. Not only on the mill, but putting it in a 5c collet on the lathe with the probe in the tail stock taper does a perfect tailstock alignment.
When I had the Grizzly mill, the headroom was occasionally an issue. Not so much on the Bridgeport.
I had bought an "import" and it was OK but developed a tick at the same place on each revolution. Annoyed me to no end. The Blake is smooth as silk and there seem to be a number around eBay at any given time. I suppose because no one uses them on CNC machines.
Best,
Stan

Offline BillTodd

  • Full Member
  • ****
  • Posts: 530
  • Colchester UK (where the lathes were made)
    • Bill's website
Re: coaxial centre finder, another method
« Reply #9 on: March 18, 2015, 09:29:18 AM »
I designed a low height right angle coax indicator for my little haighton miller

Drawings are here if you want to make one
madmodder.net/index.php/topic,3776.0.html

Bill

Offline ShopShoe

  • Full Member
  • ****
  • Posts: 462
  • Central Iowa, Central USA
Re: coaxial centre finder, another method
« Reply #10 on: March 18, 2015, 01:12:01 PM »
I've done what mklotz did. If it doesn't get your RT centered exactly, it will get you close enough to easily use finer instruments to fine-tune. I saw this idea before I did it, but I never got the original post back to look at.

This was an early project of mine for practice,  so it filled multiple needs. I have since bought an import coaxial center  finder, but that need developed when I had to center a large-ID piece for clean-up boring. (In addition, that setup created a situation where I couldn't rotate a regular indicator and also read it in the multiple positions it had to be in, so having the dial facing the same direction was needed.)

--ShopShoe

Offline zimma

  • Jr. member
  • **
  • Posts: 2
Re: coaxial centre finder, another method
« Reply #11 on: March 18, 2015, 01:35:06 PM »
For those that struggle with Z axis height when using coaxial indicators, why not remove your chuck and use a spindle collet to hold the coaxial indicator and then when done, refit the chuck and cutter. Although it takes alot more setup time, I found that there was less than an inch difference in the coaxial indicator arm of my blake indicator and a cutter held in my clarkson chuck.

Graham

Online mklotz

  • Full Member
  • *****
  • Posts: 2620
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: coaxial centre finder, another method
« Reply #12 on: March 18, 2015, 02:15:25 PM »
Marv, is that Nelson's site? I have wondered if he was still around. Seems like there were some real growing pains for a while over there but I stopped visiting it a long time ago, no criticism of the site, just wasn't my cup of tea.

I never paid any attention; I sure hope it wasn't.

I used Google Images to find a picture of a DIY Zero-It and that was the first reasonable one that popped up.
Regards, Marv
Home Shop Freeware
https://www.myvirtualnetwork.com/mklotz

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3781
  • Springfield, Tennessee. USA
Re: coaxial centre finder, another method
« Reply #13 on: March 18, 2015, 06:34:00 PM »
Sorry Marv, I went to bed early.  That is the way I thought it worked and the way I have used it,  albeit,  under power.  It does seem a bit funny,  how, one end you watch for it to jump and the opposite end you watch for it to settle . Hmm,  sounds like a day at the track  ;)

E

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #14 on: March 18, 2015, 08:30:59 PM »
Hi Guys,

I thought you might like to see one that I made a while back.

I used a cheap laser pointer from Aldi.  It works surprisingly well.
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Offline BillTodd

  • Full Member
  • ****
  • Posts: 530
  • Colchester UK (where the lathes were made)
    • Bill's website
Re: coaxial centre finder, another method
« Reply #15 on: March 18, 2015, 10:28:49 PM »
Hi Guys,

I thought you might like to see one that I made a while back.

I used a cheap laser pointer from Aldi.  It works surprisingly well.

Now that is neat  :-)

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #16 on: March 24, 2015, 04:05:51 PM »
I used a cheap laser pointer from Aldi.  It works surprisingly well.
That's neat. If I understand - it will paint an exaggerated circle around the true center, so you move the x,y until it coincides?
- about how wide is the laser dot itself?
- can you use this for open 'holes' like a pre-drill or rotary table arbor hole, or does it need to be plugged with a point or scribe center?
- I guess varying the distance (z-axis in case of mill) kind of focuses the trace diameter?

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #17 on: March 29, 2015, 12:09:13 PM »
It's on my list of items to make Baron, thanks for posting the picture!

About 2 minutes in I think:

<a href="https://www.youtube.com/watch?v=otSjut1iGGk" target="_blank">http://www.youtube.com/watch?v=otSjut1iGGk</a>
« Last Edit: March 29, 2015, 12:17:57 PM by Arbalest »

Offline Mosey

  • Full Member
  • ****
  • Posts: 1598
  • Rosemont, New Jersey, USA
Re: coaxial centre finder, another method
« Reply #18 on: March 29, 2015, 03:43:30 PM »
This guy is shmart!
Mosey :ThumbsUp:

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #19 on: March 29, 2015, 07:25:05 PM »
Very useful demo. At 4:08 he says 'accurate to 50 microns' (~0.002"). How do you suppose that was determined? That kind of what I was wondering about width of laser trace. What is typical for these pointer gadgets? Does anyone have some links of where to get them?

The example of a centering on a vertically positioned shaft was very interesting because the laser trace hoop appears at a tilted angle around the OD, kind of magnifying the off-center deviation viewed in horizontal plane from X & Y and thus maybe could be even more accurate than the trace width? Maybe if you put a gauge pin or polished bearing ball in an existing hole that needed to be centered, that principle might work?

Definitely going to have to make one of these. Good post!




Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #20 on: March 29, 2015, 10:09:01 PM »
Hi Guys,

Glad you liked mine.  :pinkelephant:   Thanks for looking.

Some pictures and a crude drawing below.  I cut the Aldi pointer in half so I could use just the laser bit, particularly since it embodies the batteries and on/off switch.  The laser spot is a couple of mm in diameter.  However I did notice that when I focused it, by moving the mill head up/down, there is a really tiny black spot in the very centre.  This makes it very easy to align on a scribed line or a pop mark.  A hole is even easier.  I spin mine at about 600 rpm.

One thing to watch out for is the strobe effect from the florescent lights in the workshop.  As you vary the speed of spin the laser circle breaks up into smaller and smaller segments.  This had me confused for a minute, until it dawned on me, why.

Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #21 on: March 30, 2015, 09:48:38 AM »
Top man, thanks for that. Angles quoted on other units folks have made seem to be between 9-11° as well. Do you know what the power of your Laser is? 5mw seems to be a popular choice at the moment.

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #22 on: March 30, 2015, 09:12:28 PM »
HI Guys, Arbalest

I haven't a clue about the laser power, but I don't think it's as high as 5mw.  I do recall a yellow warning label on the side of the unit, It might have said on there.  But since I sawed it in half and threw the top bit away.  :hammerbash:    I've just had a close look at the picture with the label !  It says "<1mw" class 2.

Incidentally the fact that the two bores intersect at the bottom is deliberate.  :)   It was done so that the laser couldn't fall out and it holds the laser firmly in place.

 
« Last Edit: March 30, 2015, 09:16:58 PM by Baron »
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #23 on: April 01, 2015, 07:46:10 PM »
Sorry, I just cant leave this topic alone. :)
I was trying all the el-cheapo pointers I could lay my hands on in stores. The little keychain types are the right size for direct mounting in the carrier tube & self contained battery. But when I examined the dot, I was kind of dismayed at how wide & sloppy edged they were. In their defense, they are meant to hilite things on a screen, not my center finder gadget. But ideally we want as small as possible. ~1mm seems to be the smallest I could find on websites, but the store ones were a sloppy edge 2-3mm.

I went on an ebay hunt. Some quantify they dot size, others/most don't. Some talk about focal length of lenses (which I assume is related to dot size?). The mW power thing seems to be indicative of power. Low is better for us.

I'm tempted by these 'modules', but not really clear on what that infers. I'm guessing you cant just hook up DC voltage to the diode, you need the little black bits controller board? But these look interesting if I understand correctly, nice smallish size? can anyone shed more light (pun) on these things, what I should be looking for? I also hav eother ideas for other similar alignment gadgets.

http://www.ebay.ca/itm/5pcs-650nm-5mW-Red-Laser-Line-Module-Focus-Adjustable-Laser-Head-5V-good-/251688838898?pt=LH_DefaultDomain_0&hash=item3a99d2e6f2


Online sco

  • Full Member
  • ****
  • Posts: 1693
  • Location: Northants UK
Re: coaxial centre finder, another method
« Reply #24 on: April 01, 2015, 08:02:34 PM »
My interest has been piqued by these as well - we need a laser pointer expert!

Simon.
Ars longa, vita brevis.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #25 on: April 01, 2015, 09:16:14 PM »
From what I've read, 5mw is perhaps a bit too powerful for our use. 1mw on the other hand may require dimming of workshop lighting to see properly. Some have said that green lasers appear brighter to our eyes than red of the same power. From this my best guess to date is something like this may be more suitable?

Link for green 1mw laser removed: Looking at it again it does say high power and that the battery runs out quickly?!

It does concern me though that some suppliers call 1mw green lasers "powerful". It makes me wonder if the quoted power output is correct?!

We do indeed need an expert to help us get through some of the possible hype. Safety is paramount.
« Last Edit: April 01, 2015, 09:23:05 PM by Arbalest »

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #26 on: April 01, 2015, 09:23:32 PM »
Hi Guys,

I wouldn't worry too much about the spot size !  Yes smaller is better, but...  If you recall I mentioned that you could focus the ring down to a small spot and that I had noticed that it had a very small black centre.  As a guesstimate this black dot is 0.2 mm in diameter.

The laser diode is just that, a diode.  It's no different than an LED.  In most laser pointers there are simply three or four small cells (battery).  In the laser pointer that I used there are three 1.2 volt cells about 6 mm in diameter. No resistors, just an on/off switch.  It relies on the internal resistance of the cells to limit the amount of current that the laser diode can draw.  In the case of mine, about 0.003 ma (3 milliampere).

If you want to use a higher voltage or a battery that can supply more current, then you will need a resistor to limit the current.  There is a formula that can be used to calculate the resistor value.  You will need to know the diode forward voltage and the current that you need to pass through it.  The diode will have a maximum current rating that you must not exceed,  although from zero up to that maximum current value will determine how bright the laser will be.

Subtract the laser diode voltage from the battery supply voltage and then divide this voltage by the required current, this will give the resistance required.
Ohms Law  R = V / I

Hope this helps clarify things.
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #27 on: April 01, 2015, 09:25:59 PM »
I would avoid green lasers.  Higher risk of eye damage.  1mw red is plenty bright enough.
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #28 on: April 01, 2015, 09:32:51 PM »
Ok, thanks for that 1mw red then!

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #29 on: April 02, 2015, 03:54:07 AM »
I wonder if the gadget was held in a lathe chuck/collet, could it similarly align a tail stock center? I would think any observed elliptical 'hoop' trace might actually exaggerate any lateral or height run-out & allow pretty precise setup, no? Maybe with the right angle geometry one could laser trace directly inside the tailstock MT arbor bore for that matter?

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #30 on: April 02, 2015, 04:01:53 AM »
I wouldn't worry too much about the spot size !  Yes smaller is better, but...  If you recall I mentioned that you could focus the ring down to a small spot and that I had noticed that it had a very small black centre.  As a guesstimate this black dot is 0.2 mm in diameter.
I noted you mentioned that before. My laser pointer doesn't have that center hole, its solid red. But I should try it on metal just to be certain. Do you think that's kind of a laser pointer lens aberration, kind of like the magnifying glass focal length principle? I wont make analogous comments about concentrating the ring of a magnifying glass to the point of spontaneous insect combustion & a misspent youth, lest the animal rights activists are monitoring :)

Offline rodw

  • Full Member
  • ****
  • Posts: 51
    • Vehicle Modifications Network
Re: coaxial centre finder, another method
« Reply #31 on: April 02, 2015, 12:45:02 PM »
I have to say this is pretty cool. I emailed a mate with far more experience with Machining than I telling him it was his next project. Not long later he told me he'd ordered his lasers. I asked him what he ordered and this is what he selected http://www.ebay.com/itm/121212852782

So I ordered the same lasers! I'm kinda hoping he'll run off one for me when he fires up his CNC mill!
RodW
Brisbane, Australia

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #32 on: April 02, 2015, 05:29:50 PM »
Hi Guys, Peter,

It could very well be an aberration that is peculiar to the laser I use.  Unfortunately I have nothing to compare it with, and Aldi seem to no longer have the laser pointer for sale.  I suspect that you would have to reduce the voltage to to   http://www.ebay.com/itm/121212852782  otherwise it may be too bright to be effective.  I'll see if I can find another laser pointer for sale somewhere, buy one and have a play with it.

Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: coaxial centre finder, another method
« Reply #33 on: April 02, 2015, 07:40:39 PM »
Not long later he told me he'd ordered his lasers. I asked him what he ordered and this is what he selected

Keep us informed. That looks similar to what I was getting itchy Buy fingers on. But I noticed in the description of your example they they say focusable = yes. Do you suppose that means you just the laser diode ('light' source)? Because I also see sometimes the lens holder & lenses sold separately, example below. (There are also apparently crosshair & single line styles you can screw on, but that's of no value for our spinning application)

http://www.ebay.com/itm/6-35mm-aspherical-lens-holder-405-G-2-lens-holder-M9-0-5mm-/121492774187?pt=LH_DefaultDomain_0&hash=item1c49889d2b

http://www.ebay.com/itm/5pcs-5mm-Collimating-lens-Focusing-Lens-Laser-Diodes-/121224004668?pt=LH_DefaultDomain_0&hash=item1c3983843c

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Online sco

  • Full Member
  • ****
  • Posts: 1693
  • Location: Northants UK
Re: coaxial centre finder, another method
« Reply #35 on: April 10, 2015, 03:28:39 PM »
I'm still thinking about making one of these laser pointer centre-finders - to get a really small dot would it work to put a piece of foil tape over the lens with a pin hole in it?

Simon.
Ars longa, vita brevis.

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1272
  • The "Naki" New Zealand
Re: coaxial centre finder, another method
« Reply #36 on: April 10, 2015, 03:51:26 PM »
Hi Simon,
 I have a laser center / edge finder, i brought the polarizer unit latter, this allows you to focus the dot. I see from there web site they now include the polarizer & have up rated the laser module. Having followed this thread I've been thinking that it should be possible to use it to build one of these. Not sure how you could make a polarizer but may be a Google would help  :killcomputer:  :Lol:

Cheers Kerrin
Get excited and make something!

Online sco

  • Full Member
  • ****
  • Posts: 1693
  • Location: Northants UK
Re: coaxial centre finder, another method
« Reply #37 on: April 10, 2015, 03:53:20 PM »
Thanks Kerrin - Can you post a link to the website,

Cheers,

Simon.
Ars longa, vita brevis.

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1272
  • The "Naki" New Zealand
Re: coaxial centre finder, another method
« Reply #38 on: April 10, 2015, 04:00:23 PM »
Hi Simon,
  here you go...  http://www.lasercenteredgefinder.com/main.html
Just had a look & they sell the polarizer as a separate part, you would just have to make yours to fit, or save the hassel & buy the whole thing! I find it quite useful, both for picking up cross lines & setting lathe tools to height, & setting the vice up on the mill....

Cheers Kerrin
Get excited and make something!

Online sco

  • Full Member
  • ****
  • Posts: 1693
  • Location: Northants UK
Re: coaxial centre finder, another method
« Reply #39 on: April 10, 2015, 04:44:32 PM »
Thanks again - expensive but looks very good.  I don't suppose you have the mini version - I can't see anywhere on the site what the overall height of the unit is.

Cheers,

Simon.
Ars longa, vita brevis.

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1272
  • The "Naki" New Zealand
Re: coaxial centre finder, another method
« Reply #40 on: April 10, 2015, 05:12:38 PM »
Hi Simon,
 Sorry no, I have the orginal. Can get some dimension of it if you would like, it would be latter as I'm at work, night shift. Had it for quite a few years now. The guys are usually quite quick at answering question. Yep not the cheapest item but I find it handy. My dad liked it & he brought one & a friend of his having seen his.

Cheers Kerrin
Get excited and make something!

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #41 on: April 11, 2015, 03:21:27 PM »
Hi Guys,

The easiest and probably the quickest way to get polarized material is sunglasses.  Though another source that is freely available but requires dismantling is dead laptop screens or flat screen monitors.  These have, usually two sheets in them.  Don't break the florescent tubes, because of the mercury content and don't break the glass sandwich because the liquid crystal is quite nasty.  Other than that there are other useful sheet materials there.

Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Offline BaronJ

  • Full Member
  • ****
  • Posts: 139
  • Grumpy Old Git !
Re: coaxial centre finder, another method
« Reply #42 on: April 11, 2015, 03:25:08 PM »
Hi Guys,  almost forgot.

I just got one of these:  5mw red laser.  Its absolutely useless !
Its far too bright.  The spot is rectangular in shape.  At the distances it needs to be used at a 2.5 X 5 mm spot is far too big.
So this is one to be avoided.

I did try to measure the spot size of mine, and its about 2 mm in diameter, not quite round, it has a small flat on one side.  I think that is why I get a tiny black dot in the centre.

I'm still looking for something like the original one that I got from Aldi.
Best Regards:  Baron.

I don’t regret the things I’ve done, I regret the things I didn’t do when I had the chance.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #43 on: April 11, 2015, 03:39:52 PM »
To get a really small dot would it work to put a piece of foil tape over the lens with a pin hole in it?

Simon.

I read on another forum that someone has tried this and yes, it does work apparently!

Offline rodw

  • Full Member
  • ****
  • Posts: 51
    • Vehicle Modifications Network
Re: coaxial centre finder, another method
« Reply #44 on: April 17, 2015, 09:06:58 AM »
I have to say this is pretty cool. I emailed a mate with far more experience with Machining than I telling him it was his next project. Not long later he told me he'd ordered his lasers. I asked him what he ordered and this is what he selected http://www.ebay.com/itm/121212852782

So I ordered the same lasers! I'm kinda hoping he'll run off one for me when he fires up his CNC mill!

Well, the two lasers turned up today. I had a bit of a play with running them off 3.3 volts and 5 volts stolen from an Arduino and it seems they have current limiting circuitry built in so you can power these directly from 3 to 5 volts. When I started to play i played arou d with 680R and 330R resistors before deciding to run it via a direct connection to a power source.

I found an old LED torch with 3 x AAA batteries in it. Thats 4.5 volts so somewhere in the middle. I turned up an adapter that replaced the torch lens out of Acetal (Delrin) and removed all the LEDs. I now have an awesome pointer that shoots the length of my yard and beyond. The focus is achieved by turning the threaded knurled end. As said before, it is very bright but adding a resistor will fix that and I dont't think the focus needs changing for the length of the mill Z axis travel.

It will be a while before we build the centreing gadget as I helped my mate out for a project by ordering some bolts against my account for a project he's working on. Went from $70 for 12 bolts to $1.68 each. Hopefully, it will earn a CNC version of this...
RodW
Brisbane, Australia

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #45 on: April 21, 2015, 01:32:00 PM »
Here's another thread on the subject over on MM.

http://madmodder.net/index.php/topic,10573.0.html

Offline Frank Boyle

  • Full Member
  • ****
  • Posts: 48
Re: coaxial centre finder, another method
« Reply #46 on: May 14, 2015, 08:30:05 PM »
To centre my rotary table, I remove the tooling from the quill and using a large spherical glass ball that I bought for this purpose,I hold the ball in the quill and lower it onto the table centre bore and adjust x/y until fits.It is quite accurate and then I fit the table chuck insert which has a centre mark which I check with a sticky pin centred on a tool in the quill.I do have a laser centre finder and an optical centre finder but this works for me.
Frank

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #47 on: May 15, 2015, 12:39:51 AM »
I Use two types for all my work
low cost is
http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=945082&PMAKA=636-7060
Higher cost
http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=952232&PMAKA=607-4907

Lasers good for a start point fast only

Good Luck
Dave

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15294
  • Hampshire, england.
Re: coaxial centre finder, another method
« Reply #48 on: May 15, 2015, 08:33:52 AM »
Hi Dave,

Welcome to the forum. Any chance of posting an introduction to yourself in the introduction section? (And I am interested to know what that lathe is you are using for your avatar  :))

Jo
Enjoyment is more important than achievement.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #49 on: May 15, 2015, 11:32:24 AM »
I don't yet have an RT as the Vertex HV4 is out of stock at Chronos at the moment. When I get one though I'm planning on using a rotary laser on a MT2 centre to set it up. Assuming I've finished making the RL by then. :naughty:

Online sco

  • Full Member
  • ****
  • Posts: 1693
  • Location: Northants UK
Re: coaxial centre finder, another method
« Reply #50 on: May 15, 2015, 02:19:16 PM »
My method for centering the RT on the mill;

Loosen RT holding down bolts
Put a hard centre in the mill quill
Lower the quill down so the point is pushed into the hole in the middle of the RT
Tighten the RT holding down bolts
Zero the DRO

Simon.
Ars longa, vita brevis.

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #51 on: May 16, 2015, 12:41:03 AM »
The avatar  is a South Bend 9A umd Tool Room lathe made in 1949
I just posted in Introduce Yourself
Introduce myself Dave from Clovis CA

Dave

Hi Dave,

Welcome to the forum. Any chance of posting an introduction to yourself in the introduction section? (And I am interested to know what that lathe is you are using for your avatar  :))

Jo

Offline CHP

  • Full Member
  • ****
  • Posts: 74
  • cheers
Re: coaxial centre finder, another method
« Reply #52 on: May 16, 2015, 12:36:12 PM »
It's on my list of items to make Baron, thanks for posting the picture!

About 2 minutes in I think:

<a href="https://www.youtube.com/watch?v=otSjut1iGGk" target="_blank">http://www.youtube.com/watch?v=otSjut1iGGk</a>


this is the link for all the measurements and instruction how to build the center finder
that you see in the video  :pinkelephant: :pinkelephant:


https://drive.google.com/drive/folders/0ByWaTeq__NX1eWtXQjIwWnU3V0E
12x36 lathe,Seig7x10 lathe, Taig lathe
9x29 Mill, Emco 55 CNC mill.......

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #53 on: May 16, 2015, 02:01:22 PM »
One photo tell it all
Note the size of spot on the ruler over 0.20" [.5mm] good for new machinist and drill work only
The coaxial center finder can repeat with in 0.0002" [0.005mm] or less
The old wiggle and electronic edge finder will repeat with in 0.0015 [0.038mm] with good eye site and machinist.
Yes I do know the adds will say electronic edge finder will repeat to 0.0002 only under best conditions / machinist.
The best I have found is Centering Scope http://www.mscdirect.com/product/details/06539332?rItem=06539332


Dave




« Last Edit: May 16, 2015, 02:17:16 PM by smithdoor »

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #54 on: May 16, 2015, 07:43:13 PM »
One photo tell it all

Dave

It does indeed, that's a stationary laser dot not the rotary laser in the link above.

.002" or even slightly better is easily good enough for the stuff I've made to date.

Offline CHP

  • Full Member
  • ****
  • Posts: 74
  • cheers
Re: coaxial centre finder, another method
« Reply #55 on: May 16, 2015, 09:14:15 PM »
this is knot a well known program because it's  very hard to find  :shrug:
on the Internet but it's a charm to use. :ThumbsUp:
and even if they don't mention it it does work with Window 7 32 and 64 bits
enjoy
Luc
http://miketreth.mistral.co.uk/centrecam.htm

BTW I use an 8meg camera with factory LED
« Last Edit: May 16, 2015, 09:36:33 PM by CHP »
12x36 lathe,Seig7x10 lathe, Taig lathe
9x29 Mill, Emco 55 CNC mill.......

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #56 on: May 16, 2015, 10:20:49 PM »
My method for centering the RT on the mill;

Loosen RT holding down bolts
Put a hard centre in the mill quill
Lower the quill down so the point is pushed into the hole in the middle of the RT
Tighten the RT holding down bolts
Zero the DRO

Simon.

I like the simplicity of this Simon.  ;) I may try using a large ball bearing between the quill and the RT.

this is knot a well known program because it's  very hard to find  :shrug:
on the Internet but it's a charm to use. :ThumbsUp:
and even if they don't mention it it does work with Window 7 32 and 64 bits
enjoy
Luc
http://miketreth.mistral.co.uk/centrecam.htm

BTW I use an 8meg camera with factory LED

A webcam and software sounds a bit involved but I would imagine the accuracy could be very good.
Using antiquated software is a real drawback though...  :Jester: some kind of WiFi webcam and Android or IOS would be more fun.  :naughty:

Offline CHP

  • Full Member
  • ****
  • Posts: 74
  • cheers
Re: coaxial centre finder, another method
« Reply #57 on: May 16, 2015, 10:37:11 PM »
Arbalest;
 imagine the precision of an 8meg camera   ::)
and then an "antique software" how old do you think
the solid edge finders are   :cheers:
12x36 lathe,Seig7x10 lathe, Taig lathe
9x29 Mill, Emco 55 CNC mill.......

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #58 on: May 16, 2015, 11:34:19 PM »
Edge finders aren't affected by computer viruses and don't need software support.  :DrinkPint:

Windows 10 is due out this summer.  ;)

Offline CHP

  • Full Member
  • ****
  • Posts: 74
  • cheers
Re: coaxial centre finder, another method
« Reply #59 on: May 16, 2015, 11:43:03 PM »
BTW Window 10 is already out as a BETA version
12x36 lathe,Seig7x10 lathe, Taig lathe
9x29 Mill, Emco 55 CNC mill.......

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #60 on: May 17, 2015, 12:03:17 AM »
The each marks on the ruler is 0.020" the laser dot looks bigger in the photo
I think would work great for wood work, farm work and steel fab work.
But to use it for machine work NO
Most machine work needs to be at least 0.005" [0.13mm]
I even have a scope for some type work to with in 0.0001" [0.0025mm]

Dave


One photo tell it all

Dave

It does indeed, that's a stationary laser dot not the rotary laser in the link above.

.002" or even slightly better is easily good enough for the stuff I've made to date.

Arbalest

  • Guest
Re: coaxial centre finder, another method
« Reply #61 on: May 17, 2015, 10:13:00 AM »
Take a look at the video.  ;)

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #62 on: May 17, 2015, 02:13:03 PM »
I saw video great add
Then I look closer
A true laser count the waves this just a spot of light
For some types of work it will

Dave

Take a look at the video.  ;)

Offline smithdoor

  • Full Member
  • ****
  • Posts: 75
    • https://groups.yahoo.com/neo/groups/southbendlathe9/info
Re: coaxial centre finder, another method
« Reply #63 on: May 17, 2015, 02:14:19 PM »
I saw video great add
Then I look closer
A true laser count the waves this just a spot of light
For some types of work it will work.

Dave

Take a look at the video.  ;)

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal