CNC'ing the 7x12 mini lathe - Episode 14 - lead screws and motors

[@624Dudley]

Leadscrew powered by Pratt & Whitney! I’m envious.

[@RotarySMP]

Smallest Pratt motor ever :)

[@alphadog6970]

Love these videos my dude. You are doing everything that i can only dream of

[@RotarySMP]

Thanks for watching. Just go for it. A small project step at time.

[@Engineerd3d]

I can't wait. Picking up pointers for cncing my own mini lathe.

[@RotarySMP]

Thanks for watching. I look forward to seeing your conversion too.

[@TidyThreads]

Just At the right time. Inspired me to go finish my warp beam and make the ends of my shafts.

[@RotarySMP]

I look forward to seeing that. Suscribed...

[@RotarySMP]

I just watched your videos. That is a seriously ambition project you have taken on. Respect.

[@TidyThreads]

@@RotarySMP Here is one i made earlier well 8 years ago.The top machine is 1930s the bottom 1950s. (: kzbin.info/www/bejne/ppeqfnuvoNCendU

[@RotarySMP]

@@TidyThreads Cool. Thanks. I wonder how many thousand of km of fabric that loom has woven? Is this an insane :) hobby for you, or to you restore these machines to put them back into commercial service?

[@TidyThreads]

@@RotarySMP Not as many km as you think. I worked out we have woven about 40km on it and it's weaving almost every day. Check out Toyota air jet looms and see how fast they are (: I do restore them to be put back to work. We have more modern looms (1979) but they can't do what the old ones do and that's what the customers want. No such thing as spare parts for these looms and each one is a little different so parts are interchangeable about 50% of the time, hence why i have stared to learn about machining. Funny thing is that they are called Hattersley Standard. Our customers want The machine from under the stairs to be running by January. That's just one half of the machine as well. We have a very rare loom to put under it that came out of a half falling down welsh barn. They had to take a wall out to get it out. Then the hauliers almost lost their lorry and looms down a welsh mountain and had to get craned out. Yep lots to do and hope i can make some videos on the journey (:

[@RB-yq7qv]

Great content again enjoying the build

[@RotarySMP]

thanks for watching.

[@rickpalechuk4411]

Great series... soon to be alive! Thanks for sharing, Cheers

[@RotarySMP]

Hope so! Thank for watching.

[@alexanderpaaskeborjesson3574]

Great video, every week I look forward for your Sunday uploads during our self quarantine here in Stockholm, Sweden. I'm also very curious about how you will deal with the tailstock, that's the part that I have the most trouble with on my mini lathe. Thank you!

[@RotarySMP]

Thanks for the feedback. Yep, the tail stock is the worst POS on these machines, at least mine is. My solution so far has been to put it off :) The easiest way to check tailstock alignment, needs you to turn a boss on the chuck to the same diamter as the ram, so I wont get to that till the spindle is turning.

[@ant-x816]

Great work! I am very curious how rigid the machine is going to be with all the upgrades. Thanks for sharing!

[@RotarySMP]

Thanks for watching. I addressed bed rigidity at the end of episode 6 and into episode 7.

[@nikond90ful1]

Thanks for the video. Looking good. keep safe and stay well.

[@RotarySMP]

Thanks for watching. Keep safe also.

[@pedroernestobraga]

Hi sir, maybe in future videos when you have a lack of contents to post, could you post some video talking about ur break press, would be nice see about it and do not see any of your videos about

[@RotarySMP]

Thanks for the feedback. I bought that years ago to a design from some australian wood working site. I posted to a forum here: www.cnczone.com/forums/bending-forging-extrusion-/56672-forum.html I'll note it for a future video. Thanks.

[@rengankrishnaiyer6912]

sir, where did u purchased that lead scared, for x axis

[@RotarySMP]

It is just some LH trapazoid lead screw and matching nut I got from Maedler.de.

[@rengankrishnaiyer6912]

@@RotarySMP thank you sir

[@FKreider]

Looks awesome!

[@RotarySMP]

Thanks for watching.

[@williamdavis9650]

Great series, many thanks. It surely wouldn't cost that much to have it professionally heat treated after a weld build-up and reshape?

[@RotarySMP]

Thanks for watching. True, the re-hardening is not a big issue. My train of thought is that it is unlikely that I can improve the load bearing capacity of the current 1/3 tooth through annealing, welding, a hand formed tooth, and re hardening. The probabliy of a hand filed tooth form carrying much load, without high spots causing problems seems low, based on my skills.

[@MakarovFox]

in interesting to see how the phrases in the list every time the font gets smaller

[@jonneneva4372]

I'm certainly no expert, but could a VFD replace the gearbox on the DoAll?

[@RotarySMP]

You would need a much more powerfully rated motor and VFD, as the gearbox provides a 5:1 reduction. Thanks for watching.

[@jonneneva4372]

@@RotarySMP Thank you for the good content. Keep up the good work and stay safe! :)

[@nikolaiownz]

Man thoes small clamps are super handy for sheet work

[@RotarySMP]

They really are... www.speedwaymotors.com/Cleco-Sheet-Metal-Clamps-Pack-10,4710.html

[@broganshattky2866]

Hey there. Would the Z axis ballscrew have to be aligned parallel with the bed, if so how did you achieve this?

[@RotarySMP]

Yes it does. I used large holes on the tail stock end bearing block to be able to adjust it to fit without binding.

[@LV2XPLR]

Great work. I haven't seen a mini lathe tore down and optimized to the level you went with it. Can you tell me what pitch, width & type of belts you are using to couple the servos to the lead screws & where you purchased them from?

[@RotarySMP]

They are HTD 3m sized, and I got them from Mädler.de. Thanks for watching. www.maedler.de/product/1643/1616/1001/zahnriemenraeder-htd-3m-fuer-riemenbreite-9-mm

[@cncdavenz]

Hi, How about fitting a VSD on the bandsaw. you will need to change the motor to 3 phase :-(

[@RotarySMP]

Thanks for watching. It is already running three phase. A VFD on the current motor, would be no match for the gearbox. The gearbox reduction ratio is about 5:1, so you would be so far down on the motor frequency, that the power will be way less than the same blade speed with the gearbox.

[@jimsvideos7201]

Having watched everything in this series - enthralled, I might add - I'm curious about how practical it would be to make your own saddle; it seems like the room for a more common ballscrew could be designed in easily. By extension I'm curious also about putting the Z axis screw in the center of the casting; any thoughts on that idea?

[@RotarySMP]

I also thought about machining a new saddle. It is nothing that special, and if you are going to be scraping anyways... You would loose some center height, as the screw center line would be higher and the nut a larger diameter. Putting the Z leadscrew under the bed would gain you nothing, other than being a realy PITA. You end up chasing a grail. The bed of this lathe is simply not very rigid, You would be better off starting off with a more rigid machine.

[@jimsvideos7201]

@@RotarySMP Ok thank you for the insight; I have one of these lathes in my basement and I appreciate all the wisdom.

[@RotarySMP]

@@jimsvideos7201 They are pretty handy tools, within in their limitations, but doing what I did makes little sense. I did it for two reasons. 1/ To learn to scrape a whole machine, and 2/ to start a YT channel. Neither goal was dependant on the Mini-lathe becoming a good lathe :)

[@jimsvideos7201]

@@RotarySMP That's fair, and it's pretty much what I had in mind. I have neither the budget nor the room for anything bigger or heavier, so for now I'll have to polish whatever I can get my hands on and have the experience for when I have room for anything bigger.

[@wibblywobblyidiotvision]

For your do-all shaft, you should be able to "insert" the tooth, and then file back to near enough the correct shape.

[@RotarySMP]

Thanks for the feedback. I have been mulling this over for a couple of years. It is a hardened gear, so brazing up a tooth, will destroy the heat treat. You can't easily drill into it to do an inserted tooth. I really do think there is enough remaining tooth for the loads I will put on it. The problem is getting the new bearing journal concentric with the existing ones.

[@wibblywobblyidiotvision]

​@@RotarySMP I'm assuming the gear itself is one piece with the shaft, but personally I'd anneal the lot (to make the cutting easier to do, both for the tooth and for the centres and seats), do what you have to do, and then reharden and grind the bearing seats between centres. If it was just the tooth, I'd probably build one up with weld if possible. I've also seen "quick and nasty" fixes done by drilling, tapping, loctiting a stud in place, and filing to shape (usually in cases where taking the piece out to do a proper repair would kill a production line for too long, but it works). For getting your centres concentric to two reference seats, centre the first one in the chuck, and hold the other in a 3 finger steady rest. That way your centre of rotation is guaranteed to run through the centre line of the 2 references, and you can use whatever you like to clean up the centre(s).

[@RotarySMP]

@@wibblywobblyidiotvision Thanks for the advice. The two bearing seats are close together, and the other bearing journal quite a long way from them. I did one attempt at centring it in the four jaw. A steady wont help, as the second seat is only the width of the gear forward. GUess I should just try again.

[@chrisstephens6673]

Would it be possible to buy a new gear from somewhere like HPC Gears in the UK and fit it to the old shaft or make a new one. Is it really 11DP?

[@RotarySMP]

@@chrisstephens6673 Yes, it is 11 DP 11 teeth. I inked it up and rolled it out to work out the helical angle. (since forgotten). I don't know the pressure angle. I couldn't find a vendor. Realistically, this gear has been running for decades (it is a 1957 model), with a slogged out bushing causing poor tooth engagement, and yet has zero tooth wear visible. I am guessing that Do-all only made one 2 speed gearbox, which was sized for the biggest saw that got it. This is the smallest saw, so it is completely overbuilt. Normally you have a straight gear, with entire teeth missing, so you have to do inserts for the gear train to work. This is a helical gear, with 1/3 of the tooth remaining.I can't imagine any home made repair being stronger than that 1/3 gear. It only got tooth decay as the intershaft bushing was allowed to get so slogged out that a woodruff key fell out and got between the teeth. The other option would be to put a motor on the rotary table, and use Gearotic to make a tooth path to machine a new gear.

[@richardgarwood4393]

Drill and tap the centers of the bandsaw shafts. Put a bolt in them set up in 4 jaw then face and centerdrill. Do the grinding remove temp center screws

[@RotarySMP]

THe shaft already has centers, but due to a previous weld repair, those centers are no longer concentric with the bearing journals. I have had one shot at clocking the journals in with the four jaw, and regrinding the centers with the dremel in the lathe. It improved the run out, but not enough. I need to try again.

[@richardgarwood4393]

Yes got that drill the existing holes out tap and fit a bolt. Center shaft of the journals in a 4 jaw then face and center drill bolt heads. Remove temp center bolts after jobs done. You did just require them for regrind ?

[@RotarySMP]

@@richardgarwood4393 Gotcha. Rather than moving over the damaged centers, replace then and make new (temporary ) ones. I think the shaft is hardened though.

[@richardgarwood4393]

Only one way to find out.

[@oldschool1993]

Should have run your ball screw down the center of the bed- mounted in front will rock your table and cause taper and drag cutting.

[@RotarySMP]

If I put it down the center of the bed, machining away what little ribbing the bed has it would have turned from a dry noodle to a wet noodle.

[@oldschool1993]

@@RotarySMP i did one years ago- machined away enough of the ribs to clear the ball nut, and then bolted the entire bed to a 1/2" steel plate- BTW- when making your mounts for lead screws put the mounting bolts parallel to the lead screw, then just oversize the mounting holes and the mount will self center itself in all directions - no shimming necessary. Loctite will keep things in line, but if you are OCD, just drill a couple holes for taper pins after the mount is aligned and tight. BTW- not familiar with your software, but I found that a parallel port is necessary for real time 2 way communication between your computer and driver for cutting threads in CNC mode- USB and Ethernet cannot carry the information.

[@RotarySMP]

@@oldschool1993 I am using LinuxCNC with a Mesa 7i97 card's processor taking over the step timing, and reading out the encoder. It is connected to LinuxCNC with an ethernet cable. I also use Mesa card set up driving the Maho. LinuxCNC and mesa cards is light years from Parallel port based systems.

[@oldschool1993]

@@RotarySMP The one I did was an open loop system using Mach 3 software- very inexpensive with just a hall effect sensor on the spindle to count the rpm. Was pretty accurate in turning repeating to about 0.0005" and could cut any thread you wanted.

[@MakarovFox]

funny history of the ruler

[@RotarySMP]

:)

[@gangleweed]

Now you have to make a decision.....live with the inadequacy or go for broke and design a new saddle for CNC application with crosslide sans compound slide. Not having a compound slide means you have bags of metal in the upper regions to fit substantial screws without having to compromise. In the cold hard light of day you also have to realize that for Kosher CNC use you should be thinking in terms of linear rails and ball screws, that means a totally different saddle design but a simpler one to fit AS THERE WILL BE NO SCRAPING.....centre lathe technology is a different kettle of fish. I think you can still use the existing lathe in parts to fit the CNC components to, but a redesign using the existing machine would be the more sane option. Of course that means this lathe will be forever your favorite baby and a new one would be the CNC one you want to make because you just want to sit back and watch the wheels go round. I think the 7X12 cheaper model ......A$650 on EBAY......would make a good donor for a CNC application as you would not need a tailstock or the long bed as per a manual lathe........new angular contacts for the head would be a must have. Fitting linear rails to a new lathe does mean you would have to probably mill off the raised vee slideway.....or use your favorite go to tool the angle grinder....... but you don't need it anyway with linear rails.

[@RotarySMP]

I dont want to start polishing a turd :) It stays as it is. Thanks for watching.

[@antoniovictorhilario4270]

My main takeaway from this - I'll only really want to keep the bed and ways. Hm. I'd best just build a lathe from scratch, using decent-sized linear rails and ball screws. That way I'll skip the headache of living with poor manufacturer design, and just live with my own design mistakes. I hope to not make too many mistakes.

[@RotarySMP]

That is a pretty good summary. Another good option is to look for a lathe bed frm a well designed lathe in the size you want. A Schaublin 70 for example.

[@marcosekurban]

How about an Emco (Compact 5, for instance)? Any advice for or against it?

[@geoffreyward4743]

the do-all gear,why can't you braze a new tooth in and shape it with a file.

[@RotarySMP]

Thanks for watching. It is a hardened gear. Brazing it will destroy the heat treatment. Also, their is enough tooth to do any job I will need it for. My problem is grinding the plain bearing journal concentric with the existing bearing journals.

[@geoffreyward4743]

@@RotarySMP looking for a junkyard do-all .you have to dream sometime.the price you got from do-all is the story of how american industry priced themselfs out of the markit.

[@RotarySMP]

@@geoffreyward4743 Yep, they are very proud of their gears. That intershaft bushing is the weak link in this design. To be fair, it was built in 1957, and the gear teeth have zero wear, although the bushing was completely slogged out. I love this saw. Used one in the Air Forace skin bay 3 decades ago, and when this one came up 2 hours away for €400 I jumped at it.

[@toms4123]

Great documentary, thumbs up although it would be even better without the ‘music’

[@RotarySMP]

Thanks for the feedback. It is difficult to cover the often annoying machine sounds, some like it with music, some hate it. I went overboard on many of those earlier videos. Hopefully my newer ones are more balanced.

[@DonDegidio]

Could a nut similar in design help with the backlash on the cross slide? www.bedroom-workshop.com/grinder-clarksonhomemade/0grinder-clarksonhomemade-user3.html#anchorbw1

[@RotarySMP]

Thanks for watching. I originally planned to do something like that, but there really isn't enough space in the saddle cut out. If you really committed, you could make a new saddle, but then you would size it for a good ground ballscrew.

[@rok1475]

I had good experience making backlash-free nuts for the lead screws from hard-wearing low friction plastic The trick is to drill the hole a bit smaller that you would for tapping in metal. The plastic expands a bit around the tap but then the thread in the plastic is tight around the lead screw.

[@RotarySMP]

I did the same thing with a previous version of the Z leadscrew.

[@asgharrezaei0138]

My dear you have a nice explenation but in between too much add from u tube and also not necessary items related to cnc lath conversion , good luck

[@RotarySMP]

Yeah, I just make videos of whatever I am doing that week. Not only and not always CNC lathe related. Some things people like, some they dont.

[@anthonycalia1317]

Annoying music can ruin an otherwise good video...

[@RotarySMP]

Thanks for the feedback. I am still learning when it adds and when it subtracts from the video. At which point was it especially annoying?

[@anameisrequired3729]

@@RotarySMP Music was subtle and fine. Thanks for the video!