Cross Hair Lasers.

[john_l]

I purchased some of the 5 volt (+-) cross hair lasers and I would like to make a bracket to hold one to the spindle and use the projected cross hairs to set the X and Y Zero.

I plan to mount the laser off-set of the bit center by a fixed distance in 2 directions. I need some help in writing a custom file (macro) that I can run that will move the X direction and the Y direction my fixed distances and then zero them both (Z2) at the new location. I'd like to be able to implement this file just like I do the C2 file that runs the Z Zero routine.

Any help appreciated.

[scottbot]

Me too.
I've got similar lasers and would like to do the same thing.

I too will appreciate any help.

Thanks.

[paul60]

Hi guys
where did you purchase the laser? and what cost
sound like a good idea.
i might just wire it up independently using a 5v battery

[cabnet636]

i ordered the laser from the thread i found either here or on vectric's forum and now i cannlt find it is it 5 volts? i am ready to hook mine up as well.

[dana_swift]

John & Scott, All you will need is something short and simple:

***** start of macro
M2 1.234,4.567
Z2
***** end of macro

The values of the M2 are the offsets of your laser crosshairs, and the M2 command needs to move the router over the point the crosshairs defined as zero. The Z2 command will set X and Y to zero at that point.

Save this in a file in the folder "c:\sbparts\custom". The file name should be something like "customN.sbc". Where the letter N is a single digit that is not used now. From the shopbot control program when you enter "cN" where N is the same digit it will run your program and set your zero.

I also am interested in laser crosshair and line generators, where did you get them?

D

[ryan_slaback]

When I first got my shopbot I was planning on doing the same. I even bought the lasers.

However I have found the proximity switches to work much better than I could have ever hoped the lasers to work. I engrave .03 deep with a v bit on the lines x=0 and y=0 each time I surface the table. If I need to have multiple places to do work I simply do a C3 to zero and then offset to a new spot and z2.

Right now I have origins established and engraved in the table at absolute coordinates of (0,0), (0,15) and (48,0).

It takes all the guess work and keyboard moves and nudges out of zeroing.

[ryan_slaback]

One other word of caution. If you do decide to use lasers they must be asolutely square with the table surface in both directions. Otherwise the thickness of the workpiece (and therefore the distance from the workpiece to the lasers) will be different. If the lasers are not square this will cause your crosshairs to project in a different spot than your known offset.

[knight_toolworks]

the laser is good for zeroing in new places. I use it to set up jigs then make custom files to go to them each time. when I remove them I use the laser to get them lined up again.
but myself I spindle/router mounted laser will give you fare more uses then a offset crosshair one. the dot is far smaller if you get the right one and you can use it to check placements of parts and jigs and square easier. but you do have to chuck it up to use it.

[scottbot]

Hi,
Sorry for taking so long to reply.
I'm having to lug my computer back and forth between the shop and the house. I don't have an internet connection in the shop. The laptop is on order and should be here soon.

I got my lasers from http://www.dealextreme.com The price was crazy cheap. $3.11
This is the link to the lasers http://www.dealextreme.com/details.dx/sku.5900
They came from Hong Kong and got here (Western Canada) in about 1 week.

Excellent solution Dana. Thanks for that.

Thanks for your word of caution Ryan. I hadn't thought of that but will take care to make sure they are mounted perpendicular to the table.

Scott

[john_l]

Thanks to all, especially Dana and Paul. I appreciate it.

My cross hair lasers were were $25 delivered from china, for 6 of them. I just found them on ebay, they are there most all the time and the sellers usually have both cross hair and pinpoint for close to the same cost.

I have to zero X and Y on a subsurface area of a part on many occasions (inboard of the edge or coner of the part thats laying on the bot table). This is why I think the laser may help me somewhat.

I hadn't thought about just powering with enough batteries to run it for the little it needs to be turned on each time. Thats also a great tip Paul. I was getting bogged down trying to figure a power source, usb, etc.

Many thanks everyone!

[dana_swift]

FYI if you need 5 volts, a simple way to get it is to use a 9volt transistor battery and a LM7805 you can buy from radio shack. That will set you back about 5 bucks. It has three wires, one to the 9v source, one to ground, and one with a regulated 5 volt output for your 5v laser.

If you need some other voltage they make adjustable versions of the 78xx family that require two resistors to set the output voltage.

D

[scottbot]

Couldn't you just hook it up to the 5 volt circuit on the Control Board output?
That way you could turn it on and off using the toggle when in keyboard mode which is when you would be moving into position anyway.

[dana_swift]

Scott, There is no reason at all not to use the 5V power from the SB control board, with a few caveats. The probe connector located somewhere around your Z car should have 5 volts available and adequate for the purpose. However it is not switched, but you can put in a toggle switch or whatever.

If you want to control the lasers from software, in the SB users manual page 50 read the section on "output switches".

The current limit is "about" 5MA, and that is pushing thing with low-power-Schottky logic (what today is called "TTL"), you risk slowly overheating and getting a short life from the output driver. Are you going to add a circuit to limit the Laser(s) to 5MA? (note that is SINK not SOURCE)

I just looked up laser diodes on Digikey and found the current requirements, absolute minimum is 4ma for a single laser, most diodes require 50-100ma each.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=524333;keywords=laser

If you want to switch that current from an output you will need a solid state relay, or a transistor or two.

Let me know how it goes..

D

[scottbot]

Dana,
I'm officially out of my league now.
I don't understand some of the things you mentioned and don't want to risk damaging the driver.
I'll stick to something simple like batteries or and old computer power supply with a toggle switch. I've got lots of those.
I'll post whatever I come up with.

Scott

[john_l]

Just wanted to follow up on this thread. I have mine hooked up and it's pretty slick.

I drilled a hole in the carriage a little larger than the laser diameter. Then drilled a location matching hole in the bottom of an aluminum project box from radio shack. The hole in the box is a tighter fit to the round laser body. I mounted a 2D cell battery holder (also radio shack), a little switch, and siliconed all over the laser to be sure it doesn't move around in there. I riveted the project box to the carriage and adjusted the laser before the silicone dried.

The cover is easy to remove when a battery change is required. It was a very simple installation this way.

My lasers were $25 for 6 of them so my total cost for this setup using one of them is about $12.

The laser lines are very clearly visible even under our high output, daylight shop lights.

Now I am back to setting up my custom cut file for Zeroing the X and Y. I will try to follow the suggestions above. Thanks again!


7249


7250


7251

[njandpa]

Great information thank you for the pictures. Yes, very slick!

[knight_toolworks]

though it costs more and you have to chuck it this is a more useful tool
http://www.lasercenteredgefinder.com/main.html
because you can use it to check parts lineup without worrying about offset. I have used it many times to check to make sure the demo part matches the drawing I just made and such as that.
plus the spot is far smaller so more accurate.

[john_l]

LaserCenterEdge was a consideration before I did it this way. I thought (and agree) that looked like a quality piece but I decided against it based on cost, and ironically, I actually wanted the larger crosshairs. I found out by experimenting with pinpoint lasers that the crosshair lines along the edge helped me see where I was at much more accurately. Most of the time I am zeroing to the edge of a sheet or a sign or part shape. I don't have to remove my bit, regardless of what kind of bit I have chucked and I can even zero X/Y with the spindle running if I want to.

My offset routine is saved as a Custom Cut.. "C5". I am not sure if I wrote the file correctly but it is working fine. My file is...

Z2
M2 -3.537,-4.54
Z2

[knight_toolworks]

not having to install the laser is a good thin I agree. but it does limit it's use when you want to check alignment besides a edge or corner. I want to see where the bit is going to cut. You can't really have both unfortunately.
it would be easier to see with the corsshairs. you need a crisp corner with the edgefinder but the dot is far more precise it is only a few thousands in width. I usually split the bean on a corner it's more accurate then I or my machine (G)but I can also take it to my mill drill and set that up and use it as a finer and my drill press. plus I can chick it for accuracy where you can't really see if yours is off. I just have to turn mine to see if the beam is perfectly centered.

[john_l]

I really wanted something to project the center of the bit from an angle outside the boundaries of the chuck like the sears drillpresses have. I agree, its a shame you cant have both.

I obviously haven't used mine enough yet to find the limitations but testing the accuracy of mine is as easy as "C5". If the bit isn't where I want it I wont start cutting.

I was worried about it moving around. I have pushed, pulled, knocked and shook the carriage and the project box. Surprisingly to me, I haven't seen any sign of movement in the laser lines. I guess the steel rivets are holding it tight. The silicone isnt even dry yet and nothing seems to be moving so I guess thats all good.

[knight_toolworks]

yes that would be nice. but when you change the height then it throws it off.

[beacon14]

I think what Steve may be missing is that John is projecting the cross hairs straight down and is using an offset (look at the location in his C5 shortcut) to place the crosshairs directly over the 0,0 point of the actual bit. So there are no parallax issues that would throw off the cursor location due to the height of the spoilboard or the thickness of the workpiece. As long as his offset values are correct it should work perfectly everytime, but it only works that easily for checking the 0,0 location. Steve's method allows him to trace the actual cut with the laser to determine if the entire file falls where he wants it on the workpiece, or to check locations other than 0,0.

Who said you can't have it both ways? Mount the crosshair laser like John did and also get the spot device to chuck in the spindle when desired.

[jerry_stanek]

Steve could make a small jig that would be his offsets and place that on his table to see the exact placement of his bit.

[bws]

I use a "laser trac" from Sears mounted on the spindle. It projects a line in one direction (it ajustable with clicks in the X and Y directions.l I bought a couple of these a few months ago. They went on sale here for $19.00 It is mounted on the Colombo with just the magnetic mounting that comes with it. When the gantry is in the middle of the table, the line projects from end to end (8'). My gantry is about 10" off the table.
The nice thing about this is you can lay an 8' board down anywhere in the XY plane and when the laser is on, the line will show you how to line up the edge. Just move the board until it lines up with the projected laser line.
For those of you that may be interested, here is the link. (Sears item number 00948326000)

http://www.sears.com/shc/s/search_10153_12605?keyword=laser+track (http://www.sears.com/shc/s/search_10153_12605?keyword=laser+track)

Jim

[knight_toolworks]

What I meant was that you can't really get a permanent mounted laser that will point to the center of the spindle. when height is changed it's off. this is a issue with some chop saw lasers too.
myself I don't need the laser too often for jig setup and I may be changing to bit anyway so it is not a big deal. I use it for other uses far more most of the time.

[bcammack]

I'm thinking that a couple of line-generating lasers mounted at right angles to each other on the spindle body so that they cross at the spindle center line would pretty much take parallax completely out of the equation here.

[yobot]

I am planning on installing some crosshairs on my machine in the near future, but for limited job runs where I want quick repeatability, I have found a rather simple solution. It works on the PRT's, I don't know about the PRS's.

I made up a couple of 1 X 1.5 inch maple blocks (don't remember the exact dimensions). Drilled for a flush mount epoxy rare earth magnet (or two if you are paranoid), then epoxied them in.

I drilled and tapped for a #10 screw and installed it into the block.

Anytime I need to trip a proximity switch at a temporary position on the table, I install the block(s).

Makes short work of a start position for repeated work.

YMMV.

David