New rail height?

[Les Filip]

Gerald,

Not meaning to pester you, but do have you settled on the new angle iron rail height for the new drawings? I noticed your photos in the capped rail thread mention 30mm. With any luck I'll be grinding my rails later this evening.

Thank you again for your tireless work.

[Gerald D]

Your rail height must be matched to the laser-cut profiled plates for the motor mountings - the taller the rail, the further the motors reach down to roll the pinion under the rail. On the current set of drawings, with the 24mm rail, the range of motor adjustment is for 24 to 36 tooth metric gears on 15mm tall rack and [20 to 30 tooth American gears running on 1/2" tall rack].

You also need to make the stop-blocks taller.

A taller rail is easier to grind with the JR Skate.

With the current set of drawings, you can already make the rail taller if you will only be using the 24tooth metric pinion or [20tooth American pinion]. A 30mm [1.25"] height will be okay for you now.

Guys with direct-driven motors can use fairly tall rails because there is nothing that prevents the motors from swinging further and further down. But the geared motor guys have two screwheads coming from the rack side, and these heads run in closed slots which limit the downswing. You could countersink those heads and also get the motors to swing far down.

Another consideration is aesthetics - I want the motors to sit fairly level and square. A tall rail now makes them drop at an angle.

The rail height in the new version will be 28mm [1.10"]. All the laser cut plates are currently being revised to work around this dimension.

[Les Filip]

Gerald, thanks for the reply.

[driller]

since the motor plate is not very large, why not draw up a second one with the larger distance ? for the extra $5.00 someone could have both and make that choice when installing.

Dave

[Gerald D]

Because the motor plates are small and interchangeable, that is a good reason to NOT change those plates. Besides, there were some things that needed changing on the gantry & car ends, so I prefered to make the changes there.

[DMS]

You also need to make the stop-blocks taller.
In drawing no. 10 10 248 and 10 20 248 the height of stop blocks are same as old drawings. Should I raise the height by 4 mm each, as the new rail heights are now 28 mm instead of 24mm (refer M1 10 110) ?

[DMS]

How many stopper blocks per axis required. As per drg. 2+2 I think.

[J.R. Hatcher]

Mine has 4 for the X (2 per stepper), and 4 for the Y. But I realized after welding all in place the Y only needed 2 (only 1 stepper). If I ever decided to install a second stepper on the Y car I would look like the smartest guy on earth. They really don't hurt anything being there.

[DMS]

Thanks J.R., and what about hight

[smreish]

Ajmer,
In the old dwg package, the part in # 10-20-248 is 12mm, in the new dwg pkg #10-10-248 it is 20mm. The height has changed for the stop block that is welded to the rail. Good luck. Sean

[DMS]

in old drg #10 10 248 "X -rail stopper block" h=20 mm while in new drg # 10 10 248 "X -rail stopper block" h=20 mm. Same

in old drg #10 20 248 "Y -rail stopper block" h=12 mm while in new drg # 10 20 248 "Y -rail stopper block" h=12 mm. Same

Wher's the difference :confused:
The date of issue is same in both new and old drg.

[smreish]

Well, you stumped me. I will do some more looking in my original printed set at the office to double check. With Gerald on Holiday until after the new year, you may have to wait to get an "official" answer.
Sean

[sailfl]

Sharma

To confirm the stop blocks: you need 4 total for both X and 4 total for both Y according to the drawings. One for each end of X and Y.

To confirm:
in old drg #10 10 248 "X -rail stopper block" h=20 mm while in new drg # 10 10 248 "X -rail stopper block" h=20 mm. Same

in old drg #10 20 248 "Y -rail stopper block" h=12 mm while in new drg # 10 20 248 "Y -rail stopper block" h=12 mm. Same

This information is correct. There is no difference. I believe you are asking why are the drawings the same. Gerald issued the complete set of drawings as a package and he gave the last or more current set the name Mamba. Some of the drawings in the Mamba set are different or have changed from the old set.

That is my understanding and I hope that helps.

[DMS]

Thanks all for help.
Sean,
I have printed set of both old and new. Logically h should be raised per rail increased hight.
Then should I raise h by 4 mm each ?
As for no. of blocks I should follow J.R. and Nils, the drg also show block at each end. This also seems logically right as the moving gantry hits only one stop block from one side the other side still in movement may put stress on gantry. While two stop blocks should divide kinetic energy equally.

[Doug_Ford]

I only put 2 stop blocks on the Y axis because they weren't cross drilled for the adjusting bolt. I believe the adjusting bolts were put there by Gerald so that the builder could compensate for inaccuracy when they are welded in place. If you weld 4 stop blocks on the Y axis without adjusting bolts and they aren't perfectly aligned, the kinetic energy will be put into the first one the car contacts.

[DMS]

That's correct while Y only needs two stop blocks X may require double with obviously adjustment bolts.
This needs expert comment from Gerald.

[smreish]

Gentlemen.
Doug has caught a very important point on the stop blocks....they have adjusting bolts so you can fine tune the stop point. ALSO, remember without a homing switch and active limits, the accuracy of the stop block on both the x and y axis is dependent on the "stop and hold" position of these block so you can set a "soft" zero for the x/y cutting plane. If you cutting a part and the table looses power "or you Estop instead of pause", you risk loosing your Zero on the table. Which often results in trashing the parts and starting over. I am installing stops on all rails, both ends to stop the axis' movement. Actually, I am playing with a new style of limit switch that will act as a plunger "thru the stop adjusting bolt" as an end of travel and homing switch. Dual purpose. I will start another thread on the control side of the forum detailing my research. It involves a very inexpensive PLC/Programmable Relay to run a simple "seek and home routine" and talk back to the BOB & Mach. Again, this is not really necessary for the MM or the DIY machine. I am working towards a control certification on the machine and hardened Over Travel limits are a requirement for UL/CE compliance.
Sean

[J.R. Hatcher]

Doug you are right if the Y car has only one stepper and almost all will. But if it had 2 steppers and only 1 set of stops, and the limit switch ever failed something might get torqued or even derail the Y car, I'm just not sure. With all that said you can always add the other blocks if you add another stepper. After I realized they were not going to be used I came real close to grinding them off, but then I figured why.....

[DMS]

Sean
I am installing stops on all rails, both ends to stop the axis' movement. Actually, I am playing with a new style of limit switch that will act as a plunger "thru the stop adjusting bolt" as an end of travel and homing switch. Dual purpose.

I welcome any new concept and wait for it. Meanwhile other parts are under process.