I thought it might be useful to repost my comment from the original video for viewres that missed it before it was posted. " Clamping the parallel shank of a tool by spring pressure is not used in industry for obvious reasons. Bellevile washers are used to clamp solid tapers into a socket via a drawbar where the inherent friction of the taper and drive keys stop the toolholder from spinning. The cutting tool is securely clamped in the toolholder. " Sealed collets would keep the chips out of the spindle bore. With about 2mm of free travel on a pair of Belleville washers do you need to have 1mm compression for clamping and the remaining 1 mm for unloading. If this is the approximate case as the load is non linear then the initial clamping zone of 1mm will be a small load and the unclamping extra 1mm of travel will be much higher. Would you use the clamping method of pulling the release bar back and tightening the nut by hand, then releasing the bar allowing the springs to clamp the part therefore a custom knurled nut may suffice.
Clamping the parallel shank of a tool by spring pressure is not used in industry for obvious reasons. Bellevile washers are used to clamp solid tapers into a socket via a drawbar where the inherent friction of the taper and drive keys stop the toolholder from spinning. The cutting tool is securely clamped in the toolholder.
I have had both of these mills , the Seig is a step below the Weiss . The PM version of the vm25 is a couple steps above the Weiss machine. The PM line of machines are the better deal.
Hi, thanks for your feedback. Unfortunately we don't have PM available in the UK, I think the closest we have is warco. On paper it's hard to tell the different vendors apart for what looks like essentially the same machine.
Nice work Olly 👍 Is that mysterious extra spindle poking out from the control box just for the chuck guard cover thing to sit on, or does it do something exciting?
great Demo Olly👍👍👍👍👍👍 i'm still old school, Imperial and Dials, just the way i was brought up, may be one day when i'm old and decrepid i'll fit a DRO 🤣🤣👍👍👍👍 nice one atb Kev
Hi Kev. There's definitely a place for dials, and sometimes even imperial. A dial graduated in 0.01mm increments is a whole lot more accurate than a digital version with 0.01mm precision. I don't use my mill DRO that much, but when I do it's really handy. I'm expecting the same with the lathe DRO.
@ironhead65 @JeremyMakesThings Hi both, glad it was useful, took ages to edit! For the cross slide, I think the best solution is the magnetic tape as it can be kept compact, it's just more expensive than the optical scales. I may well upgrade when I've saved a few more pennies.
Hi Olly. Fitting a DRO to my lathe was a game changer for me. Always a challenge to fit, but luckily mine was a kit designed especially for the Myford Super 7 and has an embedded solution for the cross slide. Very neat design. 👏👏👍😀
Thanks Andrew. I'm looking forward to the convenience of the DRO. I've managed without for ~17 years, but definitely shied away from jobs that needed a lot of precision. I'll look up the myford kit as it may be transferrable as a technique.
@@ollysworkshop The kit I installed is by MDRO and use magnetic scales. Because of their slim nature it means that the cross slide scale is fitted to a slim slot milled into the base of the cross slide. An incredibly neat solution. It’s proving to be very robust and accurate.
Well Done Olly, Did not know that those slides could be non linear along their length, but obviously the designer/builder did and allowed a way of correcting it. Just wondering how many units were made before they realised and did correct it, Always pays to buy 2nd or later generation products.👍 There may be a story in there for EV car buyers...
Hi Bob. I think it's the rejects that get sold off by the no-name chinese brands. It said SINO on it, which is a well known chinese brand, so should have been good, but it didn't come from them. I think the way they become non-linear is if the photo-lithography goes wrong - e.g. the photopositive of negative or whatever they use is maybe not flat, or is at an angle to the glass. I'm sure there's lots of ways they can screw it up.
I discovered +/- 0.4mm adjustable ones for about the same price - smallest possible being 1/4 inch (6mm) Also hand reaming should eliminate the run-out wobble of a fixed setup.
G'day Olly. Kudos mate, that was a bloody good idea mate. I have a similar problem with my colchester as I need a very slim scale to fit it. Hence why it still doesn't have DRO just yet. Cheers, Aaron.
Hi Aaron, it's a really "nice in theory" idea, and I wanted to do it. It could be made much better with a stronger spring (or possibly a gas strut as they have constant spring rate), or even with a continuous loop of wire that both pushes and pulls. There's been loads of great ideas in the comments, so maybe one day I'll get round to trying them.
Your idea to convert to push/pull (pull/pull) does not have to run up inside the cross slide. As it is only a wire (2 wires), the interference with the tailstock would be insignificant compared to the scale.
I think you gave up too soon. I know, easy for me to say, you obviously put in many many hours already, but hey just doing my job as a spectator. If you pull the cable straight out of the pulley and eliminate the cosine error as you mentioned, i think that is half the problem. The other half i think is not enough tension. I would try a MUCH stiffer spring, something strong enough to actually preload the nut against the leadscrew. Might have to double up or triple up on your aramid yarn. If that doesnt work then yeah, you will need to close the loop like you metioned. But I like the spring because (if stiff enough) it turns your acme nut into a zero backlash nut. If you're going to close the loop and use timibg belt you might as well ditch the linear scale and just use a rotary encoder. It would take up a lot less room. And the belts could be routed through those places where you didn't want a linear scale because it might get damaged. It would just need a low profile shield to keep chips off it.
Hi, thanks for the comment. I reckon I'll revisit this, but for the moment I've "given up" because I want to get the DRO fitted, and the lathe back in service. I agree a much stronger spring would be good, I was just working with what I had, that'll be an easy one to try. I also like the hydraulic idea that's been talked about, more just because I like it rather than it being the right solution. I would also like to try a rotary encoder. I'm really good at starting projects, less good at finishing them, so we'll see what happens.
Perhaps you could do a conversion like they do for a myford ML7 or Super seven. Mill a slot in your cross slide and glue a magnetic strip there. I bought a kit fro M-DRO ,but I'm sure you could make one yourself.
Thanks so much for this - you've saved a lot of us a lot of time. I often think up "creative" solutions that generations of real engineers have long since abandoned for very good reason!
It's a flawed design, but it was drawn up in a few hours. I'm sure if man years were spent on it, a solution could be found, but in engineering the compromise usually wins.
needs to be push-pull... two cables tensioned against each other. as you will see in applications like exhaust servo valves, throttle cables, or ailerons etc. as it isnt under load, mere fishing line will do... braided filament? lot more flexible. the cable has to pull on the slide in parallel, in line as it comes off the pulley. the angle gives a trig error... and places excessive load on the slide. using a rotary encoder, and a timing belt, with the same "stationary belt moving pulley" setup you see on larger gantry style machines... resolution will be dictated by the pulley diameter. as well as encoder... a small geared stepper will possibly achieve better resolution, but will need signal conditioning to give decent logic levels. how many pulses can you get per turn and how does that equate to travel?
I covered the push-pull idea, used Kevlar thread, and pointed out the cosine error in the video. A rotary encoder is certainly one way to go with this. I'm not sure it's worth struggling with stepper motors though.
I think every moving part adds some backlash, the fundamental physics can't be changed. Even the optical scale readers have backlash specified in the data sheets +/- 5um for the decent ones.
I encountered an application that had a push/pull hydraulic system to create an accurate and positive, backlash-free tool feed feed movement. No cable, no screws. You could still use your feed screw, the hydraulic would only move the measuring parts.
I understand the principle, makes perfect sense. But in practice I don't see how it could ever be guaranteed 100% bled free of air. Air would cause hysteresis in the measurement. You say this was actually implemented somewhere, what kind of machine was it? Was it accurate enough for this application? Like within .00001"?
@@charlesstaton8104 The original question as I understood it was, is there another way other than cables. I'm saying there is another way. I believe I did not say the method was developed. The systems were used on a wide variety of Wickes Crankshaft lathes (circa 1940? - 1970?) to rough out , and semi finish forged steel crankshafts prior to heat treat and finishing. The system is a platform for smooth control of motion by using opposed hydraulic devices. The idea is in control of motion and precision is in the measuring devices (scale, pick-up head). To answer the questions that come next, I would begin with: push a thin fluid in a small diameter piston (attached to the tool slide) in a small diameter cylinder through a tube into a matching cylinder that is attached to a head and scale to see what happens.Measure travel at the slide with an indicator compared to the the DRO. Going forward, I require recognition for the design and compensation where appropriate. Additionally, a small tank is required to supply fluid to both cylinders to accept fluid from one cylinder being pushed by the other, check valves to prevent back flow and added tube. The supply tank would be vented to room air, no pump is required. Movement of the tool slide would push to fluid back and forth resulting in travel of the reader head. Feed the tool in, head moves the read head in. Return the tool slide out, the read head moves back. All displayed on the DRO.
@@charlesstaton8104 The supply tank allows all air to rise to the surface and dissipate. There is no chance of cavitation to form vacuum fracture in the fluid because of the very low speed of the fluid. Once air remaining after assembly is bled, it will be bubble free. No pump, slow fluid movement.
Gday Olly, bloody shame this didn’t work out, it would’ve been a perfect solution for many lathes, really it’s a brilliant idea, Neil definitely had a creative mind and I hope to see more videos pop up over time on his channel, great video mate, cheers
Thanks Matty. It was certainly something I wanted to try, I knew it would have backlash, but was eye opening to see quite how much. I could spend a long time refining it, but every step in the mechanical chain adds some inaccuracy which is unavoidable.
I like the idea. It must be able to be solved or the reel type scales wouldn't work at all. Better wire options may be the stranded stainless wire used as gear cable replacement on mountain bikes, or, pike trace , even thinner stranded stainless wire used for the first few feet of a fishing line for fish with sharp teeth!.
Hi Peter, thanks for the ideas. The original wire I used was gear cable from a mountain bike, but I'll look into the stainless fishing wire, that sounds promising. There are many areas of possible improvement on this, not least is a stronger spring, but I just built it with what I had lying around. Ultimately, if the spring is strong enough it would overcome any stiction and slop in the system, but it may make it hard to turn the handwheel!
I think it wloul be easier to just read the dials instead of installing a DRO. But, of course, that's not a challenge :) This is a brilliant idea and with a bit more thinking, it would work just fine.
Hi Olly, this was a very interesting exercise and maybe there is still scope to make it work. I think your efforts would be better focussed on traditional positions for the DRO though. That said, it did remind me of the chart recorders that I was involved in making before they made a jump into graphic display with printed traces. These models had a paper tape indicator, coloured on one half such that the colour divide coincided with zero at one extreme and full scale at the other. Behind this you had cord which was wrapped around a bobbin and worked consistently, of course using this kind of system in a lathe environment would be too harsh for it I think. Not too dissimilar to the radio as already mentioned. Definitely no time wasted, well done for giving it a go. All the best!!
I like the hydraulic transfer idea, although not sure how to make that work, the I thought about a geared system and then thought there must be some sort of radial encoder too!!
OLLY, my mate !! I'm so glad you ran with this idea ! From a verbal where we bounced ideas off each other, you came up with a working model. You are right, it didn't work. But I can see so much more now you have something physical not just an image in my head. Again after seeing this wonderful work, I am thinking banding or timing belt material instead of cable. Think you are onto a winner, I really do ! Don't quit on this, I honestly think this will work. Sorry for not being around. Health is a issue and haven't been in the workshop this year. After surgery I'm hoping to be able to spend time making instead of thinking! All the very best Nell 😊😊😊
Hi Neil, hope you're doing well. Good to hear you're still kicking! I've had loads of thoughts, hydraulic transfer, solid wire, even a recirculating ball system. This was the most practical, solution, but needs a lot of tuning to get it to work. Don't worry, the old brain doesn't give up that easily, so perhaps I'll stumble upon the silver bullet at some stage. 😁👍
@@ollysworkshop see! Hydraulic transfer was and is an idea I'm working on for tattoo machines ! That's another story for another day 😊. I really like what you have done Olly. Backlash in directional changes is the issue. The 90⁰ transition is the issue. I'm still thinking metal style packing strap and pinch rollers or speedo cable ???? One of your subscribers will pull the bunny out of the hat. Wait and see! I planted the seed, you grew the idea. Someone will harvest 🤔🤔🤔😊😊😊
IMO, comparing the TouchDRO to a Standard DRO is like comparing a graphic interface to a command line interface. If you're a visual learning, like me, you'll love the TouchDRO.
Brilliant 👍. I'd never have thought of that in a million years. A similar drive cord system works perfectly between the scale and capacitor in old radios, so I guess on the lathe it just needs tuning (no pun intended). Cheers Olly 👍
Next time, start with lathe having tail stock and chuck having dead centers in machine, razor blade between centers with tail stock all the way in, then all they way out, to prove that tail stock is trammed and running concentric with chuck and spindle to start with. then swap over to concentric end point in drill chuck for same test as well (to prove no run out in drill check in tail stock as well), before you start checking what the reamer is doing a machine. My guess, reamers are to spec, and the reason that its reaming so much larger, is tolerance stacking in the machine not being corrected. I bring this up, since can hear the twang as you pull the reamer out of the work piece, and proves that your machine has tolerance staking to begin with, which have not been resolved.
Hi, thanks for the feedback. I can't disagree that an aligned tailstock would be a good thing, but I have a chinese lathe on a sheet metal stand on a wooden shed floor - it moves, so any alignment quickly goes away. Also the tailstock quill sags considerably even when only slightly extended due to slop in the bore. This is the primary cause of the movement that you see. I have had some practice with the reamers since, and have found that drilling a bit smaller results in a much closer to size hole.
Hi sorry for the delay in replying - unfortunately I gave up on my TouchDRO implementation, so I haven't been using it, and can't answer your question. Apologies.
Hi Olly, now that its fixed they'll need to start doing some usful work with it, like taking the grass cuttings down to the end of the garden!! Very enjoyable to watch well done!!
Hi Olly, very well presented. You say you're not a mechanical engineer and maybe you never studied mechanical engineering specifically, but I beg to differ this is a great idea, a great learning exercise too. Very impressive. Look forward to seeing your progress in the future. Have a great weekend
Hi David - RU-vid seems to have given up notifying me of comments - apparently I have to look for them myself now! So apologies for the delay. I'm glad you liked the concept. I will be making this real at some point, so stay tuned!
@@ollysworkshop Hi Olly, don't worry about RU-vid it seems to live in a world of it's own!! Maybe some kind of AI robot will be offended and delete this!! I will look out for future updates. All the best!!
Hi Olly, well done on reaching and surpasing the 2K subscribers mark, its richly deserved. The main housing in blue printed perfectly, those threads looked moulded👌👌 Well done for taking this on, you'll get there I'm sure, you've certainly proved the concept. Very interesting to see the Belleville washers, we had a very long stack of them fitted to some valves at work to provide a failsafe closure on loss of hydraulics. All the best!!
Hei thanks a lot for the video, I am operating a genmitsu 3030, and I have a question regarding the range limited on the kinematics, you add -400mm to +400mm isnt it out of the capabilities? For example mine is 300x300x78, should I set the range limits to -150mm to +150mm X,Y, and X from 0 to 78 or -78 to 0?
Hi, good question. I hadn't decided on what coordinate system to use (0,0 at back right where the machine homes, or front left, which seems more sensible), so I was leaving my options open by allowing either positive or negative XY values. I have another video about using G54 to set relative coordinates, which means you don't need to worry about machine coordinates, just work coordinates.
“Why would you ever need such a thing in the home shop” said no one ever (about anything) with a home shop! For me these things are about the journey, not the destination. Glad to see you’re still in the workshop Olly 👍 🇬🇧
Thanks for the upadate Olly Your project so do it your way, if anyone suggests different let them modify it Much thought gone in to that well done ATB Kev
Thanks Kev. I was blown away with the amount of feedback I got. Took a while to take it all in, but I had to stick with the original plan otherwise it's a different project. 👍
Don Dyar Machining installed a 5C collet closer very similar to this concept on his axelson. I think it was a commercially available product that he adapted to his lathe.
