# Lagun FT1 as a CNC Beginning?



## D. Kent (Oct 8, 2022)

Hello friends.

I have found a decently priced Lagun FT1 that appears in good shape with some tooling, but it is completely manual. I'm curious if there is anyone on here that is familiar with upgrading to 3 Axis on a manual mill and if so, how the Lagun fairs to other brands. From what I'm reading, they are nice mills, decent size for the garage, and just curious if this is a good candidate for future upgrades or do I hold out for a different model (FVT) or brand that has has more servo options, like a Bridgeport? If I had the money, I'd simply by one already outfit, but the cost is a tough sell past the wife, but for a few thousand $$, seems like the Lagun is a good starting platform and gets me on my way; just cautious as the variable speed might be a better platform to start with? or Lagun is so limited on parts, it would be $$$ to upgrade to old stuff? This assumes good condition; yes, wear dictates a lot.  Thanks in advance.


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## JimDawson (Oct 8, 2022)

I guess I would drag this one home if it's mechanically OK.  I have one just like it.  All the hard work is done, just needs a new controller, and as a bonus it can be operated as a manual machine, best of both worlds.









						Bridgeport Clone CNC Vertical Milling Machine - tools - by owner -...
					

Bridgeport Clone CNC Vertical Milling Machine CNC controller needs work, the owner told me it is a $500.00 part. You can fix it or remove CNC components. Nice large capacity, heavy duty mill. $1,400



					sfbay.craigslist.org
				




You can hang any servos you want on any machine, same with the controller.


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## D. Kent (Oct 13, 2022)

Thanks Jim. I'm a little leery of older stuff and support hardware / software, but I did reach out the seller and mentioned that if he gets no interest, I'd be interested in removing the CNC components since Fremont is relatively close for me. Yes, most likely will need a fair number of mechanical  parts to match my mill, but might be able to pickup a pile of NC parts as a start, for relatively cheap.....missing a $500 card.

I do have a dumb question about typical control. Do CNC systems normally rely on the motor encoder for position or does it reference a secondary scale (like a glass scale) for positioning? I'm wondering if, as I first think about DRO, are there slides that would be more desirable for future X-Y NC, if a typical system relies on them for positional accuracy? Maybe that's pie in the sky thinking, but my eventual plan to perform some conversion has me thinking I should check this box as I browse....are DRO scales used by system and if so, is there something I should be looking for in the slides? Positional accuracy tolerance? 

Thanks again.


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## JimDawson (Oct 13, 2022)

D. Kent said:


> Thanks Jim. I'm a little leery of older stuff and support hardware / software, but I did reach out the seller and mentioned that if he gets no interest, I'd be interested in removing the CNC components since Fremont is relatively close for me. Yes, most likely will need a fair number of mechanical  parts to match my mill, but might be able to pickup a pile of NC parts as a start, for relatively cheap.....missing a $500 card.



Not exactly sure what you said above.  What I meant about all of the hard work being done is that the ball screws and motors are mounted and is ready for a new controller to be stuffed into the existing electrical enclosures.  The existing controller parts are pretty much useless, but you can most likely reuse some of the power handling components.

That machine is a 4VK frame with box ways, heavier than the FT1.  Most likely made by Topwell in Taiwan. Parts are available.


D. Kent said:


> I do have a dumb question about typical control. Do CNC systems normally rely on the motor encoder for position or does it reference a secondary scale (like a glass scale) for positioning? I'm wondering if, as I first think about DRO, are there slides that would be more desirable for future X-Y NC, if a typical system relies on them for positional accuracy? Maybe that's pie in the sky thinking, but my eventual plan to perform some conversion has me thinking I should check this box as I browse....are DRO scales used by system and if so, is there something I should be looking for in the slides? Positional accuracy tolerance?
> 
> Thanks again.



The answer is: It depends.  It could be either or both.  You really are most interested in where the table is at, rather than the motor.  This takes a lot of the error out of the system.  My preference is to use 1 micron resolution magnetic scales, and close the loop at the controller level.


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## pontiac428 (Oct 13, 2022)

You're in California, which has more Lagun mills per capita than any other state.  Lagun made a series of CNC servo versions of their popular FTV series manual mills.  As a Lagun owner, I pay attention, and I see those servo mills go for the same price as the manuals, but they seem to sell slowly because updating CNC machines is a niche hobby.  You could get one of those, pop a new controller in it, and get up and running ahead of the game.  Probably cost less and work better in the long run, too.  Is that learning curve looking like a cliff to you yet?


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## mksj (Oct 13, 2022)

I used a friends Lagun FT2 CNC, but he mostly used it in manual mode. Could do some simple programming steps if one wanted. They ke factor is what Jim Dawson mentioned is that upgrading an existing non-cnc version is probably not practical and will not be cost effective. The CNC models come with ball screws, oilers, drives, etc. so you would be replace the control system/wiring, and but not having to retrofit the mechanical s is a significant cost savings.  Parts for the Lagun can be quite expensive, I had looked at a few years ago and most needed work on the variable speed head, drives did not work and they no longer met shop tolerances. Most of the shops were converting to dedicated CNC mills. A stepped pulley belt drive would be preferable to a Reeves drives, and easier to interface a VFD and have it control the speeds. When I looked into parts for rebuilding the Reeves drive years ago it was on the $700-800 for the parts, when I started adding up all the replacement parts I decided it was not worth paying 4K, which is what they were asking at the time when I lived in Tucson, AZ.


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## Firebrick43 (Oct 13, 2022)

D. Kent said:


> Thanks Jim. I'm a little leery of older stuff and support hardware / software, but I did reach out the seller and mentioned that if he gets no interest, I'd be interested in removing the CNC components since Fremont is relatively close for me. Yes, most likely will need a fair number of mechanical  parts to match my mill, but might be able to pickup a pile of NC parts as a start, for relatively cheap.....missing a $500 card.
> 
> I do have a dumb question about typical control. Do CNC systems normally rely on the motor encoder for position or does it reference a secondary scale (like a glass scale) for positioning? I'm wondering if, as I first think about DRO, are there slides that would be more desirable for future X-Y NC, if a typical system relies on them for positional accuracy? Maybe that's pie in the sky thinking, but my eventual plan to perform some conversion has me thinking I should check this box as I browse....are DRO scales used by system and if so, is there something I should be looking for in the slides? Positional accuracy tolerance?
> 
> Thanks again.


Accuracy and repeatability is a result of the sum of the components. 1 micron scales are meaningless if the ball screw, couplers, and any reduction method (such as a gearbox) has less accuracy. 

Some manufactures such as Mazak don’t used scales and are very accurate. On larger machines they have hollow ball screws that they climate control with an oil chiller. Smaller machine don’t have the thermal growth. 

Many do use scales, mostly just as a check. If the scales position does not match the motor encoders within the range defined in the parameter table, a following error alarm will be presented to the HMI panel. 

Here is the issue however.  If you are asking these questions about a manual Bridgeport style machine you need to do more research.  

While not a bad choice for a “hobbyists” CNC, it is a poor choice for high precision CNC. 

Most good CNC vertical mills are bed mills not knee mills.  Knee mills can work ok as manual machine when you can lock an axis such as the knee, you really can’t in a 3axis CNC mode.  Bed mills have much better rigidity especially in z axis moves as there is no quill nor knee. 

If you want excellent accuracy I would suggest starting with a commercial CNC bed mill that is physically in good shape but in need of a retrofit of the Control.


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## Karl_T (Oct 13, 2022)

I see you are on the west coast. Look for a shizouka with a dead control. This is NOT a good deal but it is an example








						SHIZUOKA AN-S 3-Axis Turret Vertical Milling Machine 51x11" Table BANDIT Control  | eBay
					

Find many great new & used options and get the best deals for SHIZUOKA AN-S 3-Axis Turret Vertical Milling Machine 51x11" Table BANDIT Control at the best online prices at eBay! Free shipping for many products!



					www.ebay.com
				




I watched for one of these for years, they were always in CA.


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## 7milesup (Oct 13, 2022)

Karl_T said:


> I see you are on the west coast. Look for a shizouka with a dead control. This is NOT a good deal but it is an example
> 
> 
> 
> ...


Why do you say that is not a good deal?  I think that machine looks like it is in awesome shape, plus it already has industrial ball screws and an ATC on it.  Rip the control off of it and install a Centroid Allin1 on it, and you would (maybe) have an awesome machine.  Of course, an in-person look at it and determining servo motor compatibility with the Centroid system would be warranted.  There would be a possibility of being into that machine with a new CNC system for $7k or so.  Not bad at all.


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## JimDawson (Oct 13, 2022)

Firebrick43 said:


> Accuracy and repeatability is a result of the sum of the components. 1 micron scales are meaningless if the ball screw, couplers, and any reduction method (such as a gearbox) has less accuracy.


I would respectfully disagree.  Linear scales take ball screws, couplers, reduction gearing, and other sources of backlash out of the equation.


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## JimDawson (Oct 13, 2022)

Karl_T said:


> I see you are on the west coast. Look for a shizouka with a dead control. This is NOT a good deal but it is an example
> 
> 
> 
> ...



If you ever get out this way, bring you trailer and I'll load one up for you.  I have a spare taking up floor space in my shop, even has a fresh retrofit on it.  It really needs a new home.


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## Karl_T (Oct 13, 2022)

7milesup said:


> Why do you say that is not a good deal?  I think that machine looks like it is in awesome shape, plus it already has industrial ball screws and an ATC on it.  Rip the control off of it and install a Centroid Allin1 on it, and you would (maybe) have an awesome machine.  Of course, an in-person look at it and determining servo motor compatibility with the Centroid system would be warranted.  There would be a possibility of being into that machine with a new CNC system for $7k or so.  Not bad at all.



OK, fair deal. BUT I have seen them go for a song. I agree; put a new control on this and you got one NICE machine.

The OP should talk to Jim about his shizouka.


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## pontiac428 (Oct 13, 2022)

Firebrick43 said:


> Accuracy and repeatability is a result of the sum of the components.


 I don't disagree, but I think components are about 40% of the accuracy and repeatability formula.  The balance is the machinist, not the engineer, who sets up the paths and G-code.  There are many tricks and techniques in setting up movement that your schoolhouse engineer can't grasp, that a talented machinist with many years of experience can implement to tighten tolerances, improve finishes, speed up cycle times, and reduce waste.  It makes me sad when people think if they buy a machine and call up a .DXF of a part that they can just push a button and get perfection.  The machine is part of the equation, but the knowledge and skills are the key.  The machine is just a dumb tool with enough rigidity, power, and tolerance to execute the movement.  Whether it has linear scales or servos with rotary encoders or a bed or a knee is irrelevant to the output.


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## pontiac428 (Oct 13, 2022)

Karl_T said:


> The OP should talk to Jim about his shizouka.


Before I do...  You got 48 hours to decide.


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## Firebrick43 (Oct 14, 2022)

JimDawson said:


> I would respectfully disagree.  Linear scales take ball screws, couplers, reduction gearing, and other sources of backlash out of the equation.


No they don’t. A machine with backlash/lost motion in an x or y axis will not make true circle such as helical boring or circular interpolation in radius.  As you change one of the axis from a positive moment to a negative the back lash will rear its head and show up as oblong circles or tool marks.

A ball bar test will show this. Even before the scales are turned off for the test.

It’s not going to be overcome entirely with “skill” from the machinist either.

Only if you were just drilling holes and such were positions were made in x/y before plunging in z will scale compensate within reason.  Even then machines with lost motion can develop bad feed back loops trying to hold position due to back lash causing motors to sing/overheat and the small but huh frequency moment on the ball screw cause localized wear in spot as the balls vibrate. Seen it multiple times in the past 16 years I have been repairing CNC machines

And it doesn’t help at all the rocking in the knee of most knee mills without the knee locked if CNC’d causing perpendicularity issues.

Why would machine builder use high dollar precision ground ball screws, abec 7/9 support bearings, zero back lash couplers and even harmonic gearbox reductions costing an additional 10’s of thousands of dollars to a machine if the scales that many have already have installed could compensate for lost motion due using much cheaper components?


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## pontiac428 (Oct 14, 2022)

Firebrick43 said:


> It’s not going to be overcome entirely with “skill” from the machinist either.


Case in point, the skilled machinist knows how to code backlash compensation.  There are several G code routines to accomplish that depending on your controller.  And what knee mills rock?  In standard operation, the spindle is always dead center of the knee.  How much error does that generate from "rocking", six zeros past the decimal maybe?  I get confused over the insistence that good work isn't possible with reasonably good equipment and attention to detail in the process.  I'm not intending to be snippy, I just don't know how an ABEC 9 bearings and $2000 a pop ballscrews are going to make the difference between perfection and scrap in a one-man home shop, dig?


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## pontiac428 (Oct 14, 2022)

Hey, man, I just had to think about it while I was out walking the dog.  I get pushy sometimes when I post, and it's not my intent to belittle or naysay.  I think the point I am trying to put out is when planning a big step up, focus on the process instead of the equipment.  The equipment is part of the conversation on this board, of course, but so much is about technique, knowledge, and process.  Learning how to work within the limits of the machine and still produce good parts is a better investment than shopping for hour upon hour finding the tightest machine components and dismissing the reality that it is indeed skill that exceeds equipment.  That's why the guy with the vette gets smoked at the drag strip by the guy with the rusty '76 Nova all the time and wonders why.  It's because the guy with the fast Nova invested in knowledge and skill, while the vette guy shook bills out of his wallet instead.  It's worth a thought.


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## 7milesup (Oct 14, 2022)

JimDawson said:


> If you ever get out this way, bring you trailer and I'll load one up for you.  I have a spare taking up floor space in my shop, even has a fresh retrofit on it.  It really needs a new home.


I can't get this dang thing out of my head, even though I have a Sharp mill sitting in my shop.   If I were close to this, I would be going over there and taking a look.


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## JimDawson (Oct 14, 2022)

There is no substitute for a tight machine.  I'll concede that you are not going to convert a <$10K knee mill in the average home shop to the accuracy of a multi-million $$ DMG-Mori by adding linear scales.  Will my machine interpolate perfect circles?  No.  I have about 0.004'' backlash in the Y axis and it will hold 0.001'' on roundness.  It's just a matter of the system being able to compensate for the backlash as best it can. Linear move deviations are normally better than I am able to measure.  My knee mill is actually just a little better than my Haas.

Really the most important parameter is repeatability.  If the machine will repeat, then you can compensate for the accuracy.  If you need perfectly round holes, then use the boring head or a reamer.


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## pontiac428 (Oct 14, 2022)

Somehow I'm convinced that there is no substitute for a _rigid_ machine.  But when the computer is calling the shots a thousand times a second, and it's equipped control system is "smart" enough to enable compensation, the tiny contributions of premium tight components (read: exorbitant capital cost) are less significant than intelligent setup and movement paths (the machinist's input in precision).  We're probably working toward the same point here, a BP conversion ≠30 million dollar machine, just going about the argument differently.  I am strictly speaking in the context of the practicing _home_ shop.  We make our lives from getting the most out of what we can attain as a hobbyist or Lilliputian home business.  It's synergistic when skill meets "good enough for $10k," you can really do good work in that range.  There is no reason to give up on ever having precision over compromising to use Chinese ballscrews and ABEC 5 bearigns in a home build.


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## Karl_T (Oct 14, 2022)

I agree that RIGID machine is the most important factor.  The "sweet spot" for a hobbyist refitting old iron to a new control is a CNC knee mill with box ways and a 3 - 5 hp spindle IMHO. There are a few small bed mills that would be even better but hard to find. Tons of these old knee mills with dead controls and only worth a couple grand.

VMCs with a dead control don't bring any more but they are too big for most home shops. Refitting these with a new tool change control gets pretty involved.

IMHO refitting an asian mill drill to CNC is just a waste of money.


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## JimDawson (Oct 14, 2022)

7milesup said:


> I can't get this dang thing out of my head, even though I have a Sharp mill sitting in my shop.   If I were close to this, I would be going over there and taking a look.


You have a trailer hitch on that jet?


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## Firebrick43 (Oct 14, 2022)

pontiac428 said:


> Case in point, the skilled machinist knows how to code backlash compensation.  There are several G code routines to accomplish that depending on your controller.  And what knee mills rock?  In standard operation, the spindle is always dead center of the knee.  How much error does that generate from "rocking", six zeros past the decimal maybe?  I get confused over the insistence that good work isn't possible with reasonably good equipment and attention to detail in the process.  I'm not intending to be snippy, I just don't know how an ABEC 9 bearings and $2000 a pop ballscrews are going to make the difference between perfection and scrap in a one-man home shop, dig?


I have never advocated for high end components here for the hobbyist????  I didn't bring 1 micron scales into the discussion!.   Just the opposite.  I brought up the cost of the components to show the folly in it for the "typical hobbyist".  Several threads, ones that you yourself have been involved in I have advocated for slow speed but high torque closed loop steppers over servos as the cost/benefit ratio is not worth the higher rapid speeds for a hobbyist and I realize, that decent rolled screws and acorn or such control can result in mediocre end of CNC's but quite an acceptable accuracy for many hobbyist needs.  (.002 to .003" reliably).

In my opinion its a large leap in cost to make any manual machine into my idea of ok precision (.001"+/- reliably)  Just the cost of a low end controller that can handle true basic feedback such as an Oak is triple or more than say an Acorn.  

In post 7 of this thread I suggested in the last line that if better precision is desired, then an older bed mill than needs a control retrofit would be a better option.  A position that you and Jim liked in post 21  ??????? Seems if you have a difference of opinion than Jim here you get attacked.  

As far as rocking, I have not seen a knee mill yet that doesn't rock as you move X axis from one end to the other unless the knee is locked, most of the time several thousands of an inch.  Maybe most projects it doesn't matter but many times if perpendicularity of drilled/bored holes is required it makes a difference.  One example is I machined some combining gear box housings half's and If I didn't lock the knee when boring one bearing bore to the next, the shafts inserted into the bearings wouldn't be parallel to each other and would have troubles when being assembled to the other half of the gearbox housing.

In post 15 I mentioned point to point compensation for drilling holes G60.  Enlighten me for backlash compensation G code for circular interpolation?



JimDawson said:


> There is no substitute for a tight machine.  I'll concede that you are not going to convert a <$10K knee mill in the average home shop to the accuracy of a multi-million $$ DMG-Mori by adding linear scales.  Will my machine interpolate perfect circles?  No.  I have about 0.004'' backlash in the Y axis and it will hold 0.001'' on roundness.  It's just a matter of the system being able to compensate for the backlash as best it can. Linear move deviations are normally better than I am able to measure.  My knee mill is actually just a little better than my Haas.
> 
> Really the most important parameter is repeatability.  If the machine will repeat, then you can compensate for the accuracy.  If you need perfectly round holes, then use the boring head or a reamer.


First, you were the one that brought up uber accuracy in post #4 talking about 1 micron scales.   What good is 1 micron(0.0000393701") doing when you have .004" backlash or 101 times the resolution of a 1 micron scale?  Even 10 micron scale(10 times better resolution than the back lash) , or even 5 is a much more cost effective solution.  Many lower end commercial machines(still in the 10's of thousands of dollars only have 2 micron scales, and the cost as you go up in accuracy is exponential.  This is the only reason I started down the path talking about higher end machine components.  The rule of thumb in metrology is that you measuring tools need to be 10 times the accuracy of what tolerances your trying to measure, why do you need 100?.

 Second, who wouldn't use a boring head or reamer when ever possible, even in the 23 million dollar machines I worked on most of the hole tools were such,  Its the only way to hit 13 micron+/- tolerances on the parts I helped make.  But boring heads/bars are difficult to use on under cut grooves, under cut bores, tapered bores and large threaded holes, but accurate circular interpolation makes it easy and the tooling cheap for one off/low count jobs, like many hobbyist have?

Also boring heads/are not always possible to use, and that is what's liberating about CNC.  For example, one day I was tasked with making a replacement oval hydraulic piston for an autoblok steady rest.  I don't know how I would of done that on a mill of any kind with back lash and have good cylindricity on the ends.  Let alone where the circular path goes straight if it had back lash would result in a tool mark which would allow fluid to pass.  I don't know how the seal groove would be done either without CNC? Done on a VF3.  I am baffled; because while I don't consider haas to be high end machines by any stretch of the imagination; all of the ones in the tool room I have used were able to at least achieve .0005" tolerances without much issue if paying attention to the tools. 

Also CNC allows good accurate profiling that previously was only possible with tracing attachments an pantograph milling machines. No back lash allows lead in/lead out without tool marks on perimeter outside profiles as well.  Back lash limits climb milling and its superior surface finish to conventional milling.


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## JimDawson (Oct 14, 2022)

Firebrick43 said:


> First, you were the one that brought up uber accuracy in post #4 talking about 1 micron scales. What good is 1 micron(0.0000393701") doing when you have .004" backlash or 101 times the resolution of a 1 micron scale? Even 10 micron scale(10 times better resolution than the back lash) , or even 5 is a much more cost effective solution. Many lower end commercial machines(still in the 10's of thousands of dollars only have 2 micron scales, and the cost as you go up in accuracy is exponential. This is the only reason I started down the path talking about higher end machine components. The rule of thumb in metrology is that you measuring tools need to be 10 times the accuracy of what tolerances your trying to measure, why do you need 100?.



I brought up 1 micron resolution scales because that's what I use for my projects.  Cheap and well within the hobby price range for most users.  About the same price as 2, 5, or 10 micron scales, about $120/axis.  I want the scale resolution to be at least 10x my target tolerance, and I use 1 micron scales because they fit well with my controllers.  I typically hit the target count to +/- 1.  Is the machine that accurate overall?  Of course not, to many other variables.

Even with 0.004'' backlash, the system will automatically compensate for most of it.  The only time the backlash is really noticeable is interpolated arcs and the system is just not fast enough to 100% compensate in the transitions.


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## rabler (Oct 14, 2022)

JimDawson said:


> Cheap and well within the hobby price range for most users. About the same price as 2, 5, or 10 micron scales, about $120/axis.


Jim,
Would you mind letting me know which brand and distributor you prefer for scales?


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## JimDawson (Oct 14, 2022)

rabler said:


> Jim,
> Would you mind letting me know which brand and distributor you prefer for scales?



I have been using Ditron with good results, seem to be every bit as good as Renishaw.  I buy direct from the factory in China.


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## pontiac428 (Oct 15, 2022)

Backlash compensation makes interpolated holes round, that's what it's for.  G425 is a backlash calibration routine for x,y,z with a probe.  Backlash values are set in firmware once obtained and that's that until it needs to be updated for wear.  Good point brought up about surface finish and backlash compensation, making a precision fit between an oval piston and bore would be beyond my current and likely future abilities in my one man shop on a one man budget with no more than 20 hours on a good week to do it.  I also agree that backlash affects finish in climb as mentioned.  I got no dog in the fight as far as encoding schemes go.  Different means to achieve the same ends, or different horses for different courses, whatever one prefers.  I should probably read back in threads more often to stay on track instead of coffee ranting responses to individual posts.  Oh look, I'm doing it again.  Dang weak short-term memory here sometimes.


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## Firebrick43 (Oct 15, 2022)

G425 is not common g code, from a search of google is bringing up marlin for printers.  Do you have a link for a machine tool controller that uses it?


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## pontiac428 (Oct 15, 2022)

It's an example of a backlash compensation scheme as a pedagogical device that is laden with demagoguery.  It's more efficient to run compensation as a parametric than it is as a movement from the CPU's perspective.  It's built in to FANUC and MACH 3.  Where's the conflict?


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## Firebrick43 (Oct 15, 2022)

No conflict at all, I want to know to use it if I need it.  I looked thru my fanuc manual and don't see it which is why I asked.


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## pontiac428 (Oct 15, 2022)

I gotcha.  It's in a parameter table, which parameter number it is depends on your model.  I'm not a CNC rocket scientist, I've only done a hobby-grade build and a half and I worked as a button monkey at some point along the way.  I can't hold a candle to the full time careerists who contribute to this board.  I do know from hands-on that Fadal, FANUC, and Mach3 all have it as a parameter, though.  Only reason I expanded on the topic is because it is kind of fundamental to the whole thing, and touches on the "how much precision is enough" discussion that gets people lost through the trees at some point in the journey.  Dig into it, you might even have the capability to do ramped backlash compensation and other hybrid schemes buried in there.


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## Karl_T (Oct 15, 2022)

rabler said:


> Jim,
> Would you mind letting me know which brand and distributor you prefer for scales?



If you put scales on that tiny little toy mill you just bought   plus encoders on the servos you can get the very most possible out of that machine. You will need a galil board to do this.


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## rabler (Oct 15, 2022)

Karl_T said:


> If you put scales on that tiny little toy mill you just bought   plus encoders on the servos you can get the very most possible out of that machine. You will need a galil board to do this.


Yep, I'm playing with various possible configurations in my head.  And I haven't even got the machine home yet.


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