Machsupport Forum
General CNC Chat => Show"N"Tell ( Your Machines) => Topic started by: Mark B on July 24, 2019, 02:33:42 PM
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Well started on a project to build a small Id od grinder. Almost all the pieces are in and had a few set backs. I'm includingapic of some of the initial electronics. I'll have some questions soon but wish me luck.
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Hi Mark,
I am looking forward to following your build project - all looks good so far :)
Tweakie.
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Just got the cross slide in last night. Today I'm measuring and designing the adapter plates and mounts and figuring out heights for the main axis. 1 question I am planning on using a stepper for the spindle ( Low rpm) and a y axis for the thread grinding. Is there a way to config mach that way. 1 time keep turning 2nd move proportionally to the z axis. ( the 2nd I can do with gcode easy enough).
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100mm linear axis
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1 question I am planning on using a stepper for the spindle ( Low rpm) and a y axis for the thread grinding. Is there a way to config mach that way. 1 time keep turning 2nd move proportionally to the z axis. ( the 2nd I can do with gcode easy enough).
I am not sure I fully understand this ?
Tweakie.
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When I am grinding the od. I want the steeper to just rotate at a rpm. When i go to grind in the threading want to be able to control rotation like threading on a lathe. Slow rpm and directly proportional to movement in the z axis
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Yes it could be done where the work rotation is essentially a Rotary Axis.
Are you planning on Mach3 or Mach4 ?
Tweakie.
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Probably 4 seems more adaptable
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Made the plate to mount the x axis to the z axis. Had to get metric access for the pillow blocks (linear bearings) damn they cost. Thank God I'll be able to use imperial feathers for most of the rest. I'll post a pic tomorrow. It's still at work right now.
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Opps just reread it metric screws and imperial threads. Oh well here is the latest pic. Base plate is next on the list.
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Can a moderator turn that pic over. I sent it right side up.
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Looking good (either way up ;))
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I have a question for all of you mach pros. Am i able to define a home, soft limit and hard limit in mach. Soft limit as a stop motion but not a shut down. As an example as I'm trying to home the machine if it hits a soft limit have it turn around and go the other direction to hit the home position.
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Hi,
soft limits are effective ONLY AFTER your machine has been homed.
Your description sounds like you want to use a soft limit to turn the axis direction around to find the home switch
ie before the machine is homed. Soft limits are distances from the home position......if the home position is yet to be
defined then the soft limits are likewise undefined.
Craig
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What about a physical switch?
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Hi,
yes a physical switch would work.
How many axes do you need to do this for?
If you put a home switch(es) at or very near to the end of the axis(es) then you would always home in one direction,
there would be no need of extra switches.
Do you use Mach3 or Mach4? I contributed to a thread where a guy had home switches in the middle of his axes and wanted
some means to always home toward the switch. Using Mach4 there is a way to do so, its not all that straight forward but
it does work.
https://www.machsupport.com/forum/index.php?topic=41636.0 (https://www.machsupport.com/forum/index.php?topic=41636.0)
Craig
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I'm not set on either mach yet. I would need to do this on 2 axis. I'm trying to make this as dummy proof as possible. If all works well it will be a full production machine for untrained operators.
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Hi,
then I'd suggest mounting the home switches at or very near the end of the axes then under almost
any circumstance the homing direction will always be toward the home switches...no guessing.....no extra switches....
no tricky coding.
If you are planning to use this widely then you should consider Mach4 over Mach3 as all development of Mach3 ceased six years ago.
Whatever bugs it has it will always have.
Mach4 is, on the other hand, being actively developed. Additionally the structure, API and Lua scripting language offer very distinct
advantages in terms of flexibility and customisation which would be very appropriate if you were considering manufacturing for
non-expert operators.
Craig
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Ok i kindad felt id go with mach4 . As for home switches I'm planning on the center axis (X) having the home in the center. If it moves to far in either direction with a piece on the mandrel it will crash into the grinding wheels. I will need the room as it dresses so it could create a problem when the wheels are new.
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Hi,
OK you have decided on a central X axis home switch then you need to consider how to do it.
Have you read and digested the method I outlined in the link I posted? In particular you need to thouougly
understand both why and the implications of that method:
Should it transpire that your machine axes can or have been moved between sessions this method would fail.
The other alternative which I think you must consider is a non-volatile multiturn absolute encoder. I recommend
you look closely at the Delta A3 series servos. They have a 24 bit absolute encoder that apportions its bits into 'so many
revolutions + so many encoder counts within that revolution'. It has a battery backup so when you turn your machine on
you don't have to home it because the machine can 'remember where it is from the last session'. They are the latest and
greatest and aren't cheap.....but you get what you pay for.
Craig
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New update. Sorry it's been a while but I finally got most of the mechanical stuff done. It's at about 90 percent.
As soon as it's all done it will be hell time for me. Electronics, software, limit and home switches.
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Can a moderator please shrink the pic.