Messages

2381

General Mach Discussion / Re: Probing plugins

« on: November 18, 2013, 12:35:33 PM »

There is the original bed of nails type wizard and that is about it.

(;-) TP

2382

General Mach Discussion / Re: Engine Cam Grinding

« on: November 18, 2013, 11:23:54 AM »

I will have to dig it all out again, If I can find it all. I take it your servo only has a 500 count encoder. You may want to consider gearing it to the 4th axis say 2:1 or maybe 3:1.

(;-) TP

2383

General Mach Discussion / Re: Engine Cam Grinding

« on: November 17, 2013, 11:51:17 PM »

What I did to make it simple was to probe the lobe in the 4th axis using a flat follower shape on the probe that is the same size as a lifter face then it directly translates it into a work profile. What the engine sees.

Then second idea was to probe the lobe directly with a radius shape the same radius as the grinder wheel. That gives a direct grinding solution as a point cloud. Then I converted the points into Gcode to run on the machine.

TO make it easy when grinding time I used axis scalling to start out bigger than the contour and grind down the blank until I get back to 1:1 .

To create the blank profile I just probed the lobe using a flat disc the same diameter as the end mill (1") then milled it into rough shape close to net size. then grind the finish profile. It saved a LOT of grinding

Later on after roughing to near net shape I cut slots in the lobe then slot welded with hardface then Ground to finish contour. Or you can just flame harden before grinding.

(;-) TP

2384

General Mach Discussion / Re: Engine Cam Grinding

« on: November 17, 2013, 11:38:29 PM »

Here is a simple drawing that shows the relationship of contact around the lobe.

IF you are going to measure for duplication. You either have to use the follower shape or do a 3 part conversion to a grinding solution.

If you use a linear indicater with a point to measure the points then convert to a running contour based on follower type Then convert that to a grinding solution based on wheel diameter.

I have a the math solutions for each if you need to see it.

(;-) TP

2385

General Mach Discussion / Re: Engine Cam Grinding

« on: November 17, 2013, 07:13:01 PM »

Here is a tool path generated to do a single cylinder 2 lobe cam in mach3. You can see the crossover moves between the lobes each pass.

(;-) TP

2386

General Mach Discussion / Re: Engine Cam Grinding

« on: November 17, 2013, 02:50:51 PM »

Hiya Bobby,  Making the  hardware is simple you just create as you described. I have already did that years ago.

The problem is in generating the Gcode as you cannot simply translate the design . The problem lies in the contact point of the wheel and the lobe is a constantly changing point as the lobe rotates. It also changes with the wear and trueing of the wheel as the diameter changes.

I had this working fairly well in Sheetcam with Les's help on the post. The math is VERY complicated to do on the fly as you have to handle a LARGE number of points per rev and recalculate each rev to comp for the cut. Doing it in Sheetcam you create the path using an offset the diameter of the wheel. Then convert the path to Gcode. Scam does all the hard work that way.  Then I setup the Grinding as PAIRS of lobes and flip flop between the 2 each pass as to equalize wear and HEAT buildup as you grind. Ran the code as a sub and USE scaling the axis to grinded from a blank to the finish lobe.

The lobe will ONLY be accurate at the finished base circle as that was where the Geometry is calculated from.

I would consider at LEAST a 12"wheel minimum to lessen the wear effect of grinding .

The big boys on the block  Landis and okuma have the CPU Horsepower to do it on the fly.

Sherline used to have a CNC cam grinder for modelers. Can't say how accurate their math is but the process works.

Just a thought, (;-) TP

2387

*****VIDEOS***** / Re: Mach3 Turn CSS Mythbuster

« on: November 17, 2013, 02:11:28 PM »

OK instead of using the SSO then just update the Sspeed dro then you have unlimited response up to max spindle speeds. I have a working model running in a macropump.

It can be started/programmed via a macro M96 as to on /off ,base diameter and Max spindle speed that it cuts OUT and does no further adjustments. Once started it follows as to the position of X being the control radius.

Interesting, (;-) TP

2388

*****VIDEOS***** / Re: Mach3 Turn CSS Mythbuster

« on: November 17, 2013, 01:04:36 AM »

Just curious but could you not just look at the Xdro as diameter and use that value as a percent of Spindle over ride.

When started it would see the X value as the base to start from then as you moved towards the center mach3 would adjust the Spindle overide to increase the speed same with moving out it would slow down.

Am I missing something ??

Just a thought, (;-) TP

2389

General Mach Discussion / Re: Drill Mill Hole Primer- Suggestions?

« on: November 17, 2013, 12:42:27 AM »

So far everything you want can be done with a wizard included in Mach3 no cad/cam needed (;-)

DRILLING is your answer not MILLING.  Trying to mill 1 1/8" deep with a tiny less than 1/8 mill will be a problem, you will break many bits to boot.

Drilling that many holes will be a piece of cake using the rectangle drilling wizard. Tell it the length and wide and how many holes in each direction .and the rest of the particulars and IT will write the code for you. Load up a good colbalt drill or carbide and have at it.

I would spot drill the holes first then come back an drill them. It would be less likely to drift off position that way YES even in MDF. Start straight end straight. Run 2 seperate programs from the wizard, one for each operation (spot,drill) Then just copy the last one into the first one so that it is one long file.

(;-) TP

2390

General Mach Discussion / Re: Drill Mill Hole Primer- Suggestions?

« on: November 16, 2013, 03:45:54 PM »

You should be drilling the 1/8" holes not trying to mill them. I don't think you would be able to circle mill 1 1/8" deep with a mill less that 1/8" in diameter(;-)

I would first spot the holes then drill the holes to depth with a carbide or cobalt drill (very rigid).

(;-0 TP