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cgallery
07-11-2003, 08:59 AM
Hello. Someone mentioned in response to one of my previous posts that if I didn't use home switches to provide a reference for starting my cutting, that I could use the software and "jog" the spindle to where I wanted to start. Sort of like placing a drill bit where you want it to start drilling. After locating the spindle, I zero the software and let it go.

This strikes me as quite a bit easier and perhaps even more reliable that using home switches.

I wonder if anyone has developed some sort of laser guide I could place on the machine that would project a dot I could use for alignment on the workpiece? I sorta envision a small laser pointer adapted to fit on the end of the router bit.

Also, if I do want to use home and limit switches, what kind to people suggest for the most accurate repeatability?

Thanks,
Phil

wjbzone
07-11-2003, 09:50 AM
Phil,
I like your idea about a laser guide for zeroing the machine. If you had a light sensor that picked up the laser, you could set zero when the pickup registered. I don't know how easy it would be to keep in alignment.

Check out the picture of how I am doing it thread "my cnc hobby" (page 2 - 4th post down).

Bill.

HuFlungDung
07-11-2003, 11:22 AM
I read an article just recently on some site about just such a device used to set up serrated chuck jaws to the proper diameter. It was on that cnc instruction site
http://www.cncci.com

Look under products/helpful tools/laser jaw setter

Although "laser jaw setter" is what it is called, there is nothing stopping you from using it for other purposes. Just don't tell them when you order :D

timmyb199
09-24-2006, 09:15 PM
maybe i am simplifing it too much but couldnt you just mount a small handheld laser pointer on the x axis , it might take a litlle aligning at first but once it set should work i ahve been thinking about it for a plasma cutter to just make zeroing on work easier

tim

fpworks
09-25-2006, 01:15 PM
Since you're using your eyes to "eyeball" the laser spot, I think you're leaving a lot of accuracy and repeatability on the table. If you were able to use a type of system similar to what is used for laser "surveying" a machine tool, that would be optimal, but probably very expensive.

If you're just trying to find something like a physical point on a part, (without regards to a physical edge) a sharp point wiggler spinning in the spindle can get real close.

If you have edges to work with, the gage ring and indicator method is the most accurate/repeatable method that I can imagine.

I know these aren't as elegant as a laser locating system...I'm curious to see what you come up with!

Justin

ricklucch
12-21-2014, 11:38 AM
I developed a Laser Jaw Setter specifically used for setting jaws on the chuck accurately.

TSJ
12-21-2014, 01:59 PM
One way to get a point on the table would be to mount a laser in the router, then jog to the point needed. Or better yet to mount the laser pointer to the Z axis a known offset from the center of the router bit so it is always mounted. The URL for one used by machinists is below, they are reasonable (about $125 for battery powered and $150 for 120V).

Welcome to Laser Center/Edge Finder (http://www.lasercenteredgefinder.com/)

wizard
12-21-2014, 04:06 PM
Laser spots that you can actually see are pretty big thus not really suitable for zeroing out a machine. This especially if you need high accuracy.

Seriously I suspect you would be better off with a traditional machinist edge finder and use that to locate off a fixed datum. You would need to be able to run your spindle at a reasonably slow speed to use the edge finder.


Hello. Someone mentioned in response to one of my previous posts that if I didn't use home switches to provide a reference for starting my cutting, that I could use the software and "jog" the spindle to where I wanted to start. Sort of like placing a drill bit where you want it to start drilling. After locating the spindle, I zero the software and let it go.

You can certainly do that though it is a real pain compared to a machine that homes reliably. Homing switches and routines make life far easier.


This strikes me as quite a bit easier and perhaps even more reliable that using home switches.

Not a chance. Given a controller that can run proper homing cycles you can re home a machine on all three axis in less than a minute if the arises are relatively close to the home switches. Doing so you can get repeatability to around a thousands of an inch and even higher if using servos with encoder feedback.


I wonder if anyone has developed some sort of laser guide I could place on the machine that would project a dot I could use for alignment on the workpiece? I sorta envision a small laser pointer adapted to fit on the end of the router bit.

How about in a collet? I have seen such alignment tools so your idea has already been made into a product.


Also, if I do want to use home and limit switches, what kind to people suggest for the most accurate repeatability?

There are probably a 100,000 different limit switches and position detectors out there. Usage is a big factor in selection. For example do you need oil tight? High precision costs more generally.


Thanks,
Phil

Id suggest shopping around a bit with the online catalogs to get an idea of what can be had out there. You can easily spend $3 or $300 and not get the right switch. It isn't like you have to rush out and buy homing and axis limit switches right away as you can do your homing manually.

alan_3301
12-21-2014, 07:01 PM
This is an 8 year old thread.