Spindle Encoder - CNC Lathe Threading
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- Опубликовано: 6 авг 2024
- Threading on a CNC lathe requires a spindle encoder so the tool makes consistent pitch passes. A rotary encoder is added to a South Bend SB1001 lathe DIY CNC and attached to a Mesa 7i76e board. LinuxCNC drives the lathe to perform the threading operations. While concept is sound, a new pulley is needed to make the project perfect, but the parts will not arrive for a couple of weeks.
If researching for your own project, make life easier and start with a 1:1 pulley ratio between the spindle and rotary encoder. Glad to answer related questions in the comments.
Chapters
0:00 Introduction
2:15 Broaching timing pulley
4:10 Installation of prototype
4:55 Making support arm
6:13 Assembly of metal parts
6:50 Threading tests
9:51 Fixes
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Cast iron is so much fun to work with.
Only dislike: the black boogers :)
Neat, once you get it all settled you'll have access to constant surface speed too.
With the 1ppr signal I was able to try constant surface speed. It's great! The lathe does struggle to change speed quickly when facing, but CSS should work nicely for turning. Thank you
Very very cool Kent.
You got the maximum out of your machine again.
As always explained nicely.
best regards Stephan
Thank you Stephan! Many have already shown adding an encoder, but I'm glad to finally have gotten the project done :) Adding one to the mill now. Best wishes
Another high quality video kent!
Thank you for your consistent support Donny. Rebuilding momentum
"Gently persuading the gear to move. " *Smack* *smack* *smack*
Small hammer :)
@@kentvandervelden tappy tap tap
Very nice work, Kent. Not into CNC yet, but really like the drive system you've got set up on the headstock.
Thank you Daniel
Nice professional fixtures for the encoder and pretty little lathe. I use the encoder counter instead of index pulse. Always start threading when counter hits 0; i.e always start at the same z,x position and spindle angle / position every time.
Surely would have been some way for me to do that. The encoder that I had is pretty high resolution. I thought of the index pulse as a chance to start over if error started to accumulate. The 1:1 ratio will make the spindle ppr more manageable. Thank you
@@kentvandervelden you don't need very high ppr, only enough to cover the max pitch which will be a function of the ppr to stepper pulse ratio. You can reduce the microsteps if necessary.
Thanks
Hi Kent You may read. this1 index pulse = both encoder pulleys same pitch. I have the same lathe using acorn . and billy d cnc kit. Thanks again for all your help on the sb1001
Kent - As a reference I have an encoder mounted for the same purpose on a similar size lathe conversion. The encoder is mounted on a pivoting bracket too. However, the encoder is engaged to the spindle shaft with a plastic gear set in a 1:1 ratio. The gears are loosely meshed so there is no cantilever load as is applied by a timing belt drive. The gear backlash is irrelevant since the spindle rotation does not reverse. Because the gears are lightweight there is little cantilevered load applied to the encoder from the weight of the gear mounted to it. The encoder I use clocks 2000 PPR.
Thank you Charles. That's a great idea! I have one more encoder to mount. Something else to try.
@@kentvandervelden An additional thought Kent is - add a dead shaft on the machine and a bushing or bearing to your existing encoder timing pulley which then mounts on the dead shaft. Attach a gear to the dead shaft timing pulley which then engages the gear on the encoder. This gives more freedom to create space between the spindle and the encoder and gives a lot of choices for gear ratios that are a combination of the ratio of the timing pulley set and the gear set.
JohnSL also managed to add an electronic lead screw to their lathes. It would be interesting to compare your design with theirs.
I'll need to watch JohnSL more carefully. His mount has bearings that take the load off the encoder, that's nicer, and critical for the CUI like encoder he used. The encoder I used can have ~4lbs of side loading. I'm making a mill spindle encoder and will use bearings on it. Thank you
I think a differential signal encoder is also helpful. I have my current ELS setup running with regular ttl signals and I get errors depending on where the wire is routing and how much noise the motor is putting out. I'd love to see how you setup linuxCNC. If I could get a pi 4 i'd try linuxcnc + remora out on my smaller fully cnc'ed lathe.
You've made a nice ELS. I'm sure you could interface a differential encoder. It's a matter of using what you already have? That's how I try to operate too. Maybe checkout Machinekit too. It's a LinuxCNC split originally for Beagle Bone Black, as I understand. I struggled a lot to find a LinuxCNC setup. After lots of headaches, I bought a Mesa 7i76e card, which has a lot of support and everything just plain works with it. Thank you
That sure beats my little arbor press for broaching a keyways, and the resin prints are great, I like the idea of having such detailed prints for prototyping. Great video Kent and I only pull off threads 50% of the time manually haha...........so an encoder is kind of the opposite of a stepper ?
A coincidence, today's road trip is to purchase an arbor press. Steppers and encoders are sort of opposites :) Thank you Aaron.
I just discovered your videos and love your content! I have the same lathe and plan to keep it manual, add a DRO, but I want to do an Electronic Lead Screw for threading. The change gears are a pain. The original spindle nut really sucks, I like the spider you made, I too plan to make a spider soon. What material did you make it from? A video would be nice too ;)
Wow! Not many people have an SB1001, even more rare is to also know about violin. As fate would be, when time more generous, I had an NS Design CR4 and today a basic traditional model. I'll check out your videos; I would love to build a violin. I made the lathe spider many years ago, and I did make a blog article about it, if you are interested. Thank you
confluencerd.com/assets/kvvcreates/articles/043-Spindle-spider-for-South-Bend-SB1001-lathe/index.html
@@kentvandervelden Cool, I'll look for that article! Thanks for the reply.
Good content and just in time. If i may ask, what rotary encoder are you using because I have to buy one
On the lathe I used TRDA-2E2500VD, and on the mill I'm using TRD-SH1200VD, both from AutomationDirect. I have the lathe encoder already else I would have used one like the mill. The hollow shaft is more convenient if supporting the shaft. Be sure to check max mechanical speed and max response frequency to know if limited by the mechanics or the electrics for the speeds you are seeking.
(Hope to have the mill video done in a couple of weeks. It's a bit nicer of a mounting. Work and winter prep has been taking priority the last few months.)
Thank you
Did you ever get it straightened out? Did you need a 1:1 pully to match the one on the lathe spindle?
Yes, with 1:1 pulley everything worked well. Thanks
Hello,
did you use now the same gearsize on the encoder and dthe spindle size or a different size.Did you figured out how to manage this in linuxcnc. My problem is, that i do not find a gear for the encoder what is as big as i need for the spindle size
Yes, I use 1:1 gear ratio. You'll be able to make the needed spindle gear your CNC router. The number of pulses needed per revolution needed by LinuxCNC is small, so gear accuracy is forgivable.
The index must be on the spindle Shaft, or need to use 1:1 ratio.
Indeed, a hard learned lesson for me. The pulley on the encoder is being replaced. Thank you.
Nice work
Can plz tell its configration in linuxcnc hal file
I am facing problem in my emco pc compact 5 lathe it has optical encoader with tow sensors one is gunrating phaseA pulse and second is indexing pulse i also attached parport pins in hal file but when i enter g33 code the machine do nothing
Please see if the following link will help, specially ArcEye's example. Also, I believe you'll need to have the at-speed pin active before synchronized motion will start, even if all else is correct. Some exploring with the watch function of the HAL Configuration might be needed.
forum.linuxcnc.org/10-advanced-configuration/28136-advantages-of-supplying-phase-b-to-spindle-encoder
You may find my configuration on Github, but they might not be too useful since I used a 7i76e.
github.com/kentavv/kvvcreates/blob/master/linuxcnc/configs/sb1001_lathe/mesa/configs/my_LinuxCNC_machine/my_LinuxCNC_machine.hal
Wishing you the best of success!
You could also just not use the index from the encoder and mount a sensor somewhere on the spindle...
Good idea! The stock magnetic 1 ppr sensor on the spindle was a possibility, and originally connected to the Mesa card for measuring speed. I'm making another spindle encoder for a mill, and can make that one nicer. Thank you
@@kentvandervelden of course - the 1:1 encoder gearing is the least hassle.. I am amazed you got a complete thread without it finding the 2nd index. I suppose it was a timing thing and it just worked out. There has aways been talk about generating a synthetic index (wouldn't be the same from boot to boot of linuxcnc) but would just be based encoder count per rev...
You were talking about the double index signal problem because of that pulley ratio. I'm going to have a 36 to 18 teeth ratio on my machine (200 pulses encoder so 400 pulses per rev of shaft). If I have a seperate sensor for index signal - will it work fine? I mean, except for the 180 degree phase random hit there shouldn't be any more issues with the pulley ratio? (my encoder has an index signal but I have a seperate index signal sensor on my machine already so I should use it instead of the 2x indel signal from the encoder)? Just asking before I make any mistake. Thanks for the video!
Sounds very reasonable. The A/B phase of an incremental encoder just keep generating pulses regardless of the state of Z. I had a magnetic sensor on the spindle I could have used in the way you are purposing, but unsure of consistency of the pulse I made the pulley 1:1. You might want to check your system's consistency but comparing number of pulses per rotation marked by the index pulse. Thank you
@@kentvandervelden Alright. I will do some tests! Thank you for your support!
@@GBWM_CNC BTW: You are describing impressive projects on your channel. Great work!
@@kentvandervelden @Kent VanderVelden Thanks a lot! I'm trying to improve my skills and share with people what I know. It's nice to have an own knowledge database to share with others. Your channel brought to me some important informations. I appreciate it!
Absolute encoder is a very complicated issue I'm facing.
Please tell more. What encoder do you have and what is its interface? Thank you
If using absolute encoders with SSI (RS422/485), take a look at this. I would like to try this but the encoders are costly. If using gray code, would need a convertor. Oh, then some way to adjust stored position if not homing after a restart. OK, I can see how this gets complicated. Are you making your own multi encoder interface board? Would be very interesting.
forum.linuxcnc.org/27-driver-boards/37129-mesa-card-and-absolute-encoders
@@kentvandervelden thanks! I'm waiting for the optical encoder part from Australia. I have a lathe PCI BOB for Linux CNC, it is designed and made by my friend in HCM. Hope that my low cost project can work...;))
everyone shows how to mount the encoder but no one shows how they wired it up to the control board.
Last page of this PDF
forum.linuxcnc.org/media/kunena/attachments/3278/7i76_Anschluss.pdf
Great your video lathe's, 😊👏👏👏 @arduinomaquinas thank you man 😊👍 subscribed !