[BlueFin]

I think I have backlash , I was having some problems using my mill as a lathe with a cut off tool on some brass and starting measuring things. A test indicator was put into the spindle, I brought the Z axis down to the vise until the needle moved, then zero the indicator dial and the DRO. holding the control key and stepping .001 it takes exactly 5 button pushes to move down .005 (this would be continuing down from a previous downward motion). Then when I start pushing the page up key the first push has no physical movement but you can hear the motor turn. It takes 6 pushes .006 to move the .005 distance back up to zero, then it takes another 6 pushes to get back down to .005 because again the first .001 of the direction reversal does nothing.

So, that sucks, how do I fix this? would it be the ball nut loose on the screw? or is it the thrust bearings on the end of the ball screw? At any rate the gibs are tight enough to allow this to happen otherwise there would be no backlash at all if the head was hanging from the screw like a bowling ball hanging from a rope (not that I am suggesting that as a fix only as an observation of current function).

[philbur]

Read your inspection certificate G7 c).(chair)

Phil

I think I have backlash , I was having some problems using my mill as a lathe with a cut off tool on some brass and starting measuring things. A test indicator was put into the spindle, I brought the Z axis down to the vise until the needle moved, then zero the indicator dial and the DRO. holding the control key and stepping .001 it takes exactly 5 button pushes to move down .005 (this would be continuing down from a previous downward motion). Then when I start pushing the page up key the first push has no physical movement but you can hear the motor turn. It takes 6 pushes .006 to move the .005 distance back up to zero, then it takes another 6 pushes to get back down to .005 because again the first .001 of the direction reversal does nothing.

So, that sucks, how do I fix this? would it be the ball nut loose on the screw? or is it the thrust bearings on the end of the ball screw? At any rate the gibs are tight enough to allow this to happen otherwise there would be no backlash at all if the head was hanging from the screw like a bowling ball hanging from a rope (not that I am suggesting that as a fix only as an observation of current function).

[sharpshooter90]

I don't own a Tormach, but the principles for any machine are the same. With the weight of the head hanging on the ball screw, you will most likely not find backlash on the down stroke. However, if the thrust bearing adjustment is loose, then the screw will move upwards a bit before it bottoms on the bearing and moves the head- this would be your motor turning with no result. To test the screw for looseness, just put a dial indicator on the top of the screw and try to move the head upwards by hand or with a lever. If this shows no movement, then its probably in the ball nut itself. Good thing is that backlash compensation in your software should take care of this simple linear motion with no problem.

[MichaelHenry]

The values for the G7 parameter measured by the Tormach auditor for my mill are significantly better in all 3 axes than the acceptace criteria. I'm just curious whether or not others are seeing the same thing.

Mike

[seanreit]

My Tormach is scary accurate, sometimes I can not measure even .001 off of what I've cut. Serial number 115

[BlueFin]

Read your inspection certificate G7 c).(chair)

Phil

Ok I see three values in MM and my machine at time of inspection was better than the limits of quality. However I don't understand what those numbers mean? I looked in the owners manual for backlash adjustment and they say the Z should be between .0006" and .001", I would like to have mine closer to the .0006" if possible. I don't see any documentation on adjusting the backlash at the ball nut so I wonder what you would do if you had slop there? I will try to tighten my ball screw angular contact bearings to see how that helps.

I was looking a Hoss's video of backlash compensation in Mach 3, but I do not see that option available for the Tormach Mach3. Was it removed at the factory? or is it hidden somewhere? it would be nice to get the .00025" out of the X and Y by cheating with the software

[philbur]

The ballnuts on the PCNC 1100 are not adjustable, at least not by us mere mortals. It would have to be performed by a specialist company.

All you can adjust is the preload on the thrust bearing. The procedure is very hit and miss. It's very easy to end up with to much preload without knowing it. Also if the gib is loose this can cause the head to "nod" slightly so you could also look there. The procedure here is also very hit and miss. However in my opinion chasing Z axis backlash down from 0.001" to 0.0006" will be a fruitless task. Spend a day getting it down to 0.0006" (maybe) then breath on it and it's back to 0.001". You are fiddling on the limit of the design. Why do you need those extra 4 tenths on the Z axis anyway? When milling there are many other issues that will result in your cutter not being within 4 tenths of where you thought it was.

I would call 0.001" good (it's in spec) and make chips.

Phil

Ok I see three values in MM and my machine at time of inspection was better than the limits of quality. However I don't understand what those numbers mean? I looked in the owners manual for backlash adjustment and they say the Z should be between .0006" and .001", I would like to have mine closer to the .0006" if possible. I don't see any documentation on adjusting the backlash at the ball nut so I wonder what you would do if you had slop there? I will try to tighten my ball screw angular contact bearings to see how that helps.

I was looking a Hoss's video of backlash compensation in Mach 3, but I do not see that option available for the Tormach Mach3. Was it removed at the factory? or is it hidden somewhere? it would be nice to get the .00025" out of the X and Y by cheating with the software

[BlueFin]

I would call 0.001" good (it's in spec) and make chips.
Phil

After reading the Internet today I guess I stand corrected. It seems as though .001" "reverse idle" is the normal mode of operation for a Tormach. I also learned that commercial machine shops generally are OK with a tolerance of .0005" - .0007" and that is for a Mazak or Mori Seiki, unless of course you are making jet engines or something.

I never expected the machine to run down to .0001", but it's the damnest thing to pull the backlash out of the table, zero the indicator and watch the needle bump 10 times for each .001" of movement.

Still though, why no backlash compensation in the software? Hoss's machine had .006" or something in it and the software corrected all but about .0015" of it.

P.S. I made some chips this afternoon and was able to get my part with an intended Z height of .0600" to come out at .0595", I used a polished endmill shank at .1245" dia and slowly raised the spindle in .0001" increments until the shank would just slide under the tool tip. I typed .1245" into the DRO, bumped the head up to .125" and zeroed it. This would mean that on the down stroke the machine would always cut .001" too high because the first click would not move anything, however, when setting the z height in this manner you could still feel a very slight "tic" as you rolled the shank under the tool tip. So I would assume that "tic" would equal some cutting in aluminum if the spindle was on, so I figure the reverse stroke must have actually compensated for the acual Z hieght when the tool reached the metal.

At any rate, 1 month down and 19 years 11 months to go before I am one of those "been doing this for 20 years" machinists

[_swede]

Why do you need those extra 4 tenths on the Z axis anyway? When milling there are many other issues that will result in your cutter not being within 4 tenths of where you thought it was.

I would call 0.001" good (it's in spec) and make chips.

Phil

I agree with this to a certain extent. But, also playing the devil's advocate, I can appreciate how BlueFin wants to maximize the potential of his machine by striving for that extra accuracy.

I received Serial # 1333 and looking over all of my inspection measurements, I also received a machine that was well better than the allowed tollerances. (I haven't cut anything yet because I've been swamped at my day-job and haven't had time to finish my machine's installation :violin

However, I also realize that with time and use of the machine, many of these inspected values will grow. It's up to us as the machinist to know our tool and monitor the machine constantly. Worst case scenario: you cannot find a means to reduce this Z-axis backlash, but at least you are cognizant of it and can keep it in mind when setting up tooling / tool paths.

btw: This forum has some great discussions guys!

[_swede]

At any rate, 1 month down and 19 years 11 months to go before I am one of those "been doing this for 20 years" machinists

Hahah!

Hey, also I've been meaning to ask: any relation to Bluefin Robotics Corp. out of Boston?? Or just cooincidence? Perhaps you've answered this before.. I didn't bother to search.. Sorry!

[BlueFin]

I agree with this to a certain extent. But, also playing the devil's advocate, I can appreciate how BlueFin wants to maximize the potential of his machine by striving for that extra accuracy.

I received Serial # 1333 and looking over all of my inspection measurements, I also received a machine that was well better than the allowed tollerances. (I haven't cut anything yet because I've been swamped at my day-job and haven't had time to finish my machine's installation :violin

However, I also realize that with time and use of the machine, many of these inspected values will grow. It's up to us as the machinist to know our tool and monitor the machine constantly. Worst case scenario: you cannot find a means to reduce this Z-axis backlash, but at least you are cognizant of it and can keep it in mind when setting up tooling / tool paths.

Welcome to new Tormach ownership, it takes a strange person to drop 10 grand on something that sits in your garage and when friends come over and ask what it is they walk away even more confused as to what your talking about when you try to explain it. Then when you show them a part you made they think that's the only thing it does! :tired: And yes, I am interested in making the machine be all that it can be, I do fully understand that it is not a 100K+ Mazak, but if the documentation indicates that .0006" is attainable and if it's within my limited capability then it's worth a try. Although I am not touching it yet for 2 reasons, I believe that the bearings will "wear in" and start to slow down somewhere so when the backlash is removed it will be more stable, and 2, I am still too chicken to mess with it yet! So for now I just keep checking the machine and when I hand write code I manually add backlash comp into it.

[BlueFin]

Hahah!

Hey, also I've been meaning to ask: any relation to Bluefin Robotics Corp. out of Boston?? Or just cooincidence? Perhaps you've answered this before.. I didn't bother to search.. Sorry!

Nope, no relation. They were however the first ones to come up when I searched for anyone else who might be using that business name. Both the name and the fact that I am machining now are strange transitions. My real job for 20+ years now has been forestry related in timber harvesting and mechanized fire fighting. Mostly operating large dirty bulldozers smashing things into unrecognizable piles of debris, or felling timber down in some gawd-for-saken hole somewhere for a cable yarder to drag them out of. So now for me to stand in a clean, dry shop with the heater on and worry about .0004" is a far cry from anything I have ever done in my life.

As far as the name, I have only fished twice in my life, find it rather boring, but I became to admire the "Pelagic" lifestyle of the Bluefin Tuna and try to parallel it's habits with my own.

[_swede]

... it takes a strange person to drop 10 grand on something that sits in your garage and when friends come over and ask what it is they walk away even more confused as to what your talking about when you try to explain it. Then when you show them a part you made they think that's the only thing it does! :tired:

It's a constant battle! Luckily a good friend of mine is equally addicted to spending copious amounts of money on machining equipment and tooling.

But like you said, the general public reacts to our machines with a "is this honestly what you do for fun?" look on their face. Sometimes it is worth explaining the function of a machine/tool that little bit more, because you'll never know when it could land you a source of work. Some of my best projects are sourced by people who have a crazy idea but zero skill to bring it to fruition.

And yes, I am interested in making the machine be all that it can be, I do fully understand that it is not a 100K+ Mazak, but if the documentation indicates that .0006" is attainable and if it's within my limited capability then it's worth a try.

Absolutely!

[_swede]

My real job for 20+ years now has been forestry related in timber harvesting and mechanized fire fighting. Mostly operating large dirty bulldozers smashing things into unrecognizable piles of debris, or felling timber down in some gawd-for-saken hole somewhere for a cable yarder to drag them out of.

I just watched a special on Discovery HD on Bog Logging. Looked like a lot of fun, but I'm sure any type of timber harvesting definitely requires you to earn your money!

Please elaborate on the mechanized fire fighting! Ever deal with any fire fighting robotics? Or do you mean that in a different sense? The reason I got into mechanical engineering to begin with was because of robotics... hence why I asked about BlueFin Robotics Corp.

Kind of unrelated, but I've been itching to become a local, volunteer firefighter for a town near my home. I'm busy with National Guard/civilian job as it is, but I feel additional first-responder training would be very valuable to everything I do.

So now for me to stand in a clean, dry shop with the heater on and worry about .0004" is a far cry from anything I have ever done in my life.

It's great, isn't it? I took it for granted for a while myself too!

[sharpshooter90]

I think Smithy learned that lesson the hard way too. A while back they were selling a Chinese made bulldozer. They quickly dropped it like a hot potato- most likely because they discovered that a guy with a broken Chinese lathe in his garage is a lot easier to deal with than a guy with a Chinese bulldozer broken down in some muddy, frozen field.

[bobs_charger]

But like you said, the general public reacts to our machines with a "is this honestly what you do for fun?" look on their face. Sometimes it is worth explaining the function of a machine/tool that little bit more, because you'll never know when it could land you a source of work. Some of my best projects are sourced by people who have a crazy idea but zero skill to bring it to fruition.



Absolutely!

I know the feeling. After my day job I go into my two friends business where they own the machine and I work on it, work on projects for them, and sit and watch aluminum fly. My girlfriend asks me why i work until 12am there, so one Saturday I brought her in when machining a part and she looked at it and said thats all, this is what keeps you here so late, mind you i work 8am-5pm normal job then 5:30pm-12am (+-). Keeps me busy, extra money, and don't have to watch lame chick tv, haha.

Back on topic why is it that the machine does not operate to the tolerances it shows in the cert. According to my cert I should have no problems yet i am .004-.005" off in x, y, and z axis' . Hopefully as it was stated the bearings "seat" and everything wears in so I can either comp in dimensions or do some adjustment on the machine itself.

I also had a great experience with the machine the other weekend. After running it for about 5 hours I was on the last operation and it was drilling. The z axis started acting up and wasn't moving up the proper hieght, while the screen should the proper movement. Needless to say once it was done with one of the holes and went to the other, the bit wasn't fully out and it broke the bit :tired:. I was thinking it might be the coupler slipping but I haven't had a chance to check it out yet.

[_swede]

Back on topic why is it that the machine does not operate to the tolerances it shows in the cert. According to my cert I should have no problems yet i am .004-.005" off in x, y, and z axis' . Hopefully as it was stated the bearings "seat" and everything wears in so I can either comp in dimensions or do some adjustment on the machine itself.

I also had a great experience with the machine the other weekend. After running it for about 5 hours I was on the last operation and it was drilling. The z axis started acting up and wasn't moving up the proper hieght, while the screen should the proper movement. Needless to say once it was done with one of the holes and went to the other, the bit wasn't fully out and it broke the bit :tired:. I was thinking it might be the coupler slipping but I haven't had a chance to check it out yet.

.004-.005 is a lot. Are these values consistent or is the inaccuracy intermittent? Did you/the machine owner ever disassemble to machine for any reason (ie: installation)?

How old is the machine and what's the duty cycle like? Was it to cert from the beginning and degraded quickly for some reason?

The slipping couplers sounds possible.. but what are the chance that all three are sliping about the same amount???

[bobs_charger]

[QUOTE=_swede;535186 Did you/the machine owner ever disassemble to machine for any reason (ie: installation)?

How old is the machine and what's the duty cycle like? Was it to cert from the beginning and degraded quickly for some reason?

The slipping couplers sounds possible.. but what are the chance that all three are sliping about the same amount??? [/QUOTE]

Well the owners and I are best friends and I was working for them helpingthem out while job hunting. But when we recieved the machine and got it up and running with tools and such we first tried to do the test part that the manual talks about, the PCNC "cut out". It would not do this how it should and after a late night trouble shooting with Tormach it was determined to be a bad version of Mach 3, note I am in Cali and I forget who helped us until almost 11pm PST so about 1am their time. Once the new controller was installed things seemed ok as i would check simple parts I noticed that it was off, but I could correct the depth problem of the part by facing less material from the back.

The error is pretty constant. But recently the Z-axis did it's deal. I havent had a chance to run it sinse the other weekend because I have had to design some new parts and well life also gets in the way.

[BlueFin]

I just watched a special on Discovery HD on Bog Logging. Looked like a lot of fun, but I'm sure any type of timber harvesting definitely requires you to earn your money!

Please elaborate on the mechanized fire fighting! Ever deal with any fire fighting robotics? Or do you mean that in a different sense? The reason I got into mechanical engineering to begin with was because of robotics... hence why I asked about BlueFin Robotics Corp.

Kind of unrelated, but I've been itching to become a local, volunteer firefighter for a town near my home. I'm busy with National Guard/civilian job as it is, but I feel additional first-responder training would be very valuable to everything I do.


It's great, isn't it? I took it for granted for a while myself too!

We're probably starting to get way OT at this point, I think there is a CNCZone forum here somewhere that was setup for everything non-cnc and we could probably setup a thread there for the random things that come up. Anyway, since you asked, currently what I mean by mechanized fire fighting is the use of any kind of machinery to separate fuel from an on-coming fire. 95% of the time it is bulldozers. However a lot of mechanized logging equipment is starting to show up on the fireline, feller bunchers, forwarders, excavators etc. I am also heavily involved with equipment tracking on incidents via GPS radio trackers affixed to the equipment with the position displayed on GIS software on a laptop in the operations center. I can now use the Tormach to help me build electronics enclosures and switch panels for the devices.

Robotics is something that I have not really done much, but really want to get into someday, I think most repeative jobs that humans do can someday be relieved of the "drudgery" Why can't my trashcan just drive it's self down to the curb Tuesday night and use a simple guidance system to avoid obstacles (basketball, toy truck, etc.) then come back the next day to it's docking station for a recharge?

As far as robotics and fire, did you catch one of the "Prototype This" episodes a while back where they used the Tormach to mill out a small robot thing to carry equipment up-stairs to the roof of a high rise building? It will also bring an injured person down the stairs if needed. Pretty cool idea. Right now we in Oregon are some of the first in the country to use automated/robotic cameras on mountain tops to scan the hills for fires and when the camera sees one it sends a notification to the dispatch center and plots the location on a GIS map. I get to go to tower climbing school to help maintain/repair these cameras. There is also a big push towards the future of recon aviation on fires, it is a huge risk and cost to put a person in the air to just look around and report back. We are looking at drone aircraft with cameras to replace the current method. I really want to get in on some of that

And lastley to try and salvage some "on-topic" sense of this post, the reason why I bought the Tormach was to develop a product line of items that help those in the fire industry by making some of the jobs faster and easier. I am almost done with the first one and will "unveil" it at a trade show this spring, the other should be complete around fall of 09'.I am also building my own CNC gantry machine for router, plasma, oxy/fuel and will use the Tormach to finish the motion componants on it. The build thread can be found at, http://www.bluefincnc.com

I also put some pictures and videos that I took while at work online at these links,

http://www.bluefincnc.com/job

[ame="http://www.youtube.com/watch?v=dRWOTqO6GH4"]YouTube - Cab view of a Cat D6N shifting gears[/ame]

[ame="http://www.youtube.com/watch?v=hFyX_hdFjLI"]YouTube - D6C Dozer building fire line in Southern Oregon[/ame]