Precision limit switches and lathe homing

[ScotY]

Cool, thanks for the info! I guess I’ll try them and see. I don’t mind the cost as I only need one. Would be worth it to me to have to avoid the skim cut and measure ordeal.

Stupid question because I don’t use the lathe much and I’m not home at the moment...if I home X, then take a skim cut and measure, does the software remember the position when restarting the machine? I assume it does but never gave this much thought until now. Also, how do you adjust the homing speed?

[mick41zxr]

They are the Metrol Switches from Japan.
Very high quality & accuracy, have used them for a while with no problems.
Only issue I see is that the signal wire supplied is not shielded so you have to take that into consideration.

[cbb1962]

I use these inductive proximity switches on my CNC router. My homing routine for each axis works like this:

• move to switch at 50ipm
• move opposite direction until switch clears at 5ipm
• move to switch at .1ipm

I have found this give very accurate homing, well within the accuracy/repeatability of my machine.

Would you share your .hom file?

[slodat]

Code: Select all

; 2019-12-22 Homing file
; cncm.hom
;
N100 ;Check for open home switch
IF ![#50001] THEN M225 #100 "X Axis Home Switch Tripped!!!\nPlease Clear Before Homing\nPress Cycle Cancel To End Homing"
IF ![#50002] THEN M225 #100 "Y Axis Home Switch Tripped!!!\nPlease Clear Before Homing\nPress Cycle Cancel To End Homing"
IF ![#50003] THEN M225 #100 "Z Axis Home Switch Tripped!!!\nPlease Clear Before Homing\nPress Cycle Cancel To End Homing"
 

M106 /Z P3 F15  ;Move Z at 15 ipm until input 3 (Z axis switch) opens
M105 /Z P-3 F5  ;Back Z off Switch
M106 /Z P3 F.1  ;Move Z at 0.1 ipm until input 3 opens
M26 /Z          ;Set Z home here
M105 /Z P-3 F5  ;Back Z off Switch

M105 /Y P2 F50  ;Move Y at 50 ipm until input 2(Y axis switch) opens
M106 /Y P-2 F5  ;Back off Y Switch
M105 /Y P2 F.1  ;Move Y at 0.1 ipm until input 2(Y axis switch) opens
M26 /Y          ;Set Y home here
M106 /Y P-2 F5  ;Back off Y Switch

M105 /X P1 F50  ;Move X at 50 ipm until input 1(X axis switch) opens
M106 /X P-1 F5  ;Back X axis switch
M105 /X P1 F.1  ;Move X at 0.1 ipm until input 1(X axis switch) opens
M26 /X          ;Set X home here
M106 /X P-1 F5  ;Back X off X switch

g53 x0.1 y 0.1

N1000           ;END

[Muzzer]

I've used Omron TL-Q proximity switches on my Bridgeport Z axis to good effect. These are eddy current devices, rather than Hall effect or variable reluctance, which means they work with most metals - and their sensing distance is quite a bit shorter with non-ferrous targets than ferrous ones (steel etc). The upshot is that they are likely to be several times more accurate when used with an aluminium target and they seem to be very repeatable. See the bottom of page 6 of the datasheet.
http://www.ia.omron.com/data_pdf/cat/tl ... csm468.pdf

They are widely available on ebay etc, in both NO and NC versions.