Inlays in the forearm ...?

JC

Coos Cues
Gold Member
When dealing with hobbyist CNC machines with no home switches, which the vast majority of cue builder use, a well organized Mach 3 with properly set up soft limits and use of offsets will keep track of pretty much all the zero points we need. Once you find the points of interest and zero them you can return reliably forever so long as you don't have a pc crash prior to being able to home your machine in before quitting.

I really struggled with this entire concept until it clicked with the help of some really smart youtubers. The nice thing about you tube is they don't start calling you an idiot if you don't understand at first. You just rewind and they have the same friendly demeanor as a minute ago.

In short you find a master x-y zero in G54 and set your soft limits there over near crash limit. Then set your other soft limits near crash at the other three corners. I use the lower left corner of my machine. And never work in this offset. It's just a home reference you don't want to change. Then you set another master z-y zero for say centerline of spindle center using G55. You also never work in this offset, it's just a template to get you where you want to be. Then G56 for where you want to engrave joint protector end or whatever, etc. I have a hole drilled and tapped on my spoil board for this purpose and G57 set to find it. Mach comes set up with G54-59 for you to use so you have 5 offsets you can use as these "templates". All they are for is so you can switch to them and send your axis to zero and find your points you set up. You never actually work in these offsets.

Once you have zeroed mach to the offset template you are looking for depending on what you are doing then you switch to G59 which is your working offset. You can do whatever you want there move z up and down, x and y and tweak it to your hearts content and all you have to do to go back to start is switch to the offset you started in and zero there. Mach remembers everything based on distance from your x-y zero in G54, which is in fact your machine's mechanical zero.

When you're all done with your job you return to G54 and zero your machine so even if you turn off your computer when you start it again and begin at G54 zero your machine will be physically right where you left it as long as no one turns any screws by hand while it's sitting there.

Don't know if this is the right way to do things but it keeps you organized and seems to work well. This is how I do it anyway.
 
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JC

Coos Cues
Gold Member
Just because someone happened to be a good cuemaker does not make him into an educator, some hate sharing, others hate teaching kindergarten but do great at the graduate level. Unless of course your business depends on new arrivals and their lack of knowledge.
Chris, you've have always been and educator. :)

Mario
I spend countless hours reading and re reading Chris' book and always learn something I didn't understand the first time around when I see it again.

Without Chris I doubt I would have been able to launch.
 

cueman

AzB Gold Member
Gold Member
Silver Member
going back to my earlier post about using an engraving bit, I use Mach3 at 5% speed to jog the alignment of the bit to the drive and tail centers. Hit the zero button for that axis....and done.View attachment 601512View attachment 601513
That is how I do it on our little mill for cue inlays. It is fast, easy and gets me close enough. But on my larger aluminum and steel parts making cnc mill I use an edge finder.
 

JC

Coos Cues
Gold Member
Here is the video I watched several times to get a grasp on soft limits and offsets in mach 3 and how to use them with my CNC machines.

It was very confusing at first but once you understand these concepts thoroughly life is so much easier.

 

JoeyInCali

AzB Silver Member
Silver Member
Here is the video I watched several times to get a grasp on soft limits and offsets in mach 3 and how to use them with my CNC machines.

It was very confusing at first but once you understand these concepts thoroughly life is so much easier.

Careful with this video. Make sure you have the right direction when hitting Go To zero.
But, the video is good in general. Setting soft limits in every job is a good practice as he shows it .
 

JC

Coos Cues
Gold Member
Careful with this video. Make sure you have the right direction when hitting Go To zero.
But, the video is good in general. Setting soft limits in every job is a good practice as he shows it .
You can always screw things up if you don't pay attention. :(
 

JoeyInCali

AzB Silver Member
Silver Member
You can always screw things up if you don't pay attention. :(
And it is very EASY to screw up in cnc'ng.
Used to write codes manually .
I milled the dead center at least once .
Let me come to your place for some training .
 

conetip

AzB Silver Member
Silver Member
On my home setup, I have a piece of material that gets a hole routed into it. It is set at some nominal distance from the coordinates of the workpiece to be made. The advantages of this , is it is close to the actual job, and reduces the effects of temperature changes in the shop as well.
In the old shed, there were more than 20C or 68F changes in temp. Relying on the home position for zero was just not possible. But a hole made that can be indicated that is only a few inches away from where the real work is allowed for the repeatability that was needed. Some die tooling has a reference hole made for this very reason as well. Especially if it is to be made to very close tolerances.
As to putting inlays into the forearm of a cue, if that is what people in your area want, then go to it.
 

POOLSTICKRICK

Registered
When cutting inlay pockets in the forearm of a cue it is important to get the cutter exactly on the center line of the forearm.
Because of the round shape of the forearm, cutting to a depth of .11" at the center dont leave much room for error with a .5" wide inlay.
If it is off one side will be deeper than the other side.
Worst case is that there will not be any depth at one of the the outer edges of the pocket.

What would be a good method of setting the cutter bit exactly on the center line of the forearm?

View attachment 600907

When cutting inlay pockets in the forearm of a cue it is important to get the cutter exactly on the center line of the forearm.
Because of the round shape of the forearm, cutting to a depth of .11" at the center dont leave much room for error with a .5" wide inlay.
If it is off one side will be deeper than the other side.
Worst case is that there will not be any depth at one of the the outer edges of the pocket.

What would be a good method of setting the cutter bit exactly on the center line of the forearm?

View attachment 600907
I MADE BOTH OF THESE. THEY WORK GREAT.
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20210716_164014.jpg
20210716_162244_resized.jpg
20210716_164037.jpg
 

conetip

AzB Silver Member
Silver Member
I use gauge blocks to get the cutters on the centreline of the setup. So cut a groove on a blank, put a dowel in the groove. Measure its height then rotate 180 and measure its height again. half the difference and the cutter is on centreline. Measuring the cutter itself is not guaranteed that it actually is symmetrical or is cutting as it should be.
 

JC

Coos Cues
Gold Member
I MADE BOTH OF THESE. THEY WORK GREAT
Those are great tools for finding the center of the cue but how do they help your end mill line up with it?
I use gauge blocks to get the cutters on the centreline of the setup. So cut a groove on a blank, put a dowel in the groove. Measure its height then rotate 180 and measure its height again. half the difference and the cutter is on centreline. Measuring the cutter itself is not guaranteed that it actually is symmetrical or is cutting as it should be.
Neil,
I'm sort of slow on the uptake here and can't visualize what you are describing but would love it if you could elaborate more.

I figured actual machinists would have tricks for this and was hoping to learn some from this thread.
 

conetip

AzB Silver Member
Silver Member
So I set up a scrap piece into the dividing head/ indexer. I just by eye estimate the centre line. Then make a cut into the test piece enough to get a test roller or ball into the groove , enough that it is in there for location but out enough to see the centre line of the test roller or ball. Measure the top or the bottom of the roller or ball. Then rotate the scrap object 180 degrees. Re measure the ball or roller. The difference in the measurement halved is the actual centre line of the dividing head/ indexer. It can be measured using gauge blocks or with a height gauge or a dial indicator on the Z axis. Keep in mind the resolution of the measuring will determine the accuracy of setting the centreline. I did an exaggerated drawing to show what I am trying to explain. So hopefully you can see how the error is doubled or booked. So if you have 0.1mm difference from the cut side and the 180 deg side, then the cutter will need to be adjusted by 0.05mm.
Neil
 

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JC

Coos Cues
Gold Member
So I set up a scrap piece into the dividing head/ indexer. I just by eye estimate the centre line. Then make a cut into the test piece enough to get a test roller or ball into the groove , enough that it is in there for location but out enough to see the centre line of the test roller or ball. Measure the top or the bottom of the roller or ball. Then rotate the scrap object 180 degrees. Re measure the ball or roller. The difference in the measurement halved is the actual centre line of the dividing head/ indexer. It can be measured using gauge blocks or with a height gauge or a dial indicator on the Z axis. Keep in mind the resolution of the measuring will determine the accuracy of setting the centreline. I did an exaggerated drawing to show what I am trying to explain. So hopefully you can see how the error is doubled or booked. So if you have 0.1mm difference from the cut side and the 180 deg side, then the cutter will need to be adjusted by 0.05mm.
Neil
Quite Excellent!

This pretty much answers the OP's question from post #1 and mine as well. I knew real machinists had ways.

Thank you.

Now I will demonstrate this in a youtube video and pretend I'm smart. :D
 

Ssonerai

AzB Silver Member
Silver Member
For centering with a dividing head, i sometimes just c-drill, then drill a 3/16" hole in a piece of aluminum scrap round.
Put a 3/16" dowel in the spindle collet, and rotate the work 180. If the dowel in the spindle enters the hole smoothly without deflection, it's good.

It's easy to get very, very close first try, if an edge finder is used first.


1626617021416.png

Keep the cutting tools short and rigid. Use good collets not a jaw chuck unless the tolerances are loose.

smt
 

DaveK

Still crazy after all these years
Silver Member
It's easy to get very, very close first try, if an edge finder is used first.
I agree, and asked in post #3 if anyone used one ... seems like the obvious answer to me ... of course I am not a cuemaker.

Dave
 

JoeyInCali

AzB Silver Member
Silver Member
For centering with a dividing head, i sometimes just c-drill, then drill a 3/16" hole in a piece of aluminum scrap round.
Put a 3/16" dowel in the spindle collet, and rotate the work 180. If the dowel in the spindle enters the hole smoothly without deflection, it's good.

It's easy to get very, very close first try, if an edge finder is used first.


View attachment 602562
Keep the cutting tools short and rigid. Use good collets not a jaw chuck unless the tolerances are loose.

smt
Or chuck up a 1/4 rod in the spindle and as dead center in the turner .
Butt up the rod from the spindle to the rod in the chuck.
You are .250" from the center. Set the offset .
Or get a camera or laser crosshair .
 

conetip

AzB Silver Member
Silver Member
A lot of the routers are short on height. The edge finders work. I have the 10mm ceramic one as well as the 6mm version shown above. I still prefer the method I mention with a scrap piece to get the centreline if it really matters. The camera system does work if correctly set up as well. So does a dti as well. There are many ways to achieve the same end result. It just depends on how often you do something and the time it takes to set up each time.
 

billsey

Registered
Or chuck up a 1/4 rod in the spindle and as dead center in the turner .
Butt up the rod from the spindle to the rod in the chuck.
You are .250" from the center. Set the offset .
Or get a camera or laser crosshair .
Uh, wouldn't you be .125" from center on a .250 rod?
 
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