Step by step method for upgrading a lathe cross slide to linear ball rails.

I'm at it again, attacking my long suffering lathe. I previously made several posts about my electronic control conversions, here are some links to the previous posts.

https://www.homemadetools.net/forum/...598#post174256

https://www.homemadetools.net/forum/...662#post182609

https://www.homemadetools.net/forum/...133#post207610

https://www.homemadetools.net/forum/...280#post208119

https://www.homemadetools.net/forum/...620#post182542

Now I want to turn my electronically controlled lathe into a cam grinding machine which requires the best possible accuracy. When you are chasing tenths slide friction is the enemy of precision so the ball slides are primarily to reduce sliding friction to gain accurate positioning. I have a distant friend who is planning something similar so I made a 14 min video to pass on ideas. I thought that it might be of interest to others so here it is.

https://youtu.be/9jCVAOwIsDs

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Thanks tonyfoale! We've added your Cross Slide Linear Ball Rail Conversion to our Lathes category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-cross-slide-linear-ball-rail-conversion"> <img src="/uploads/261105/homemade-cross-slide-linear-ball-rail-converion.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-cross-slide-linear-ball-rail-conversion">Cross Slide Linear Ball Rail Conversion</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/bearing'>bearing</a>, <a href='https://www.homemadetools.net/tag/cross-slide'>cross slide</a> </div> </div> </div> </div>
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Tony I am following this project with interest, the mechanical process of cam grinding I understand but designing the desired profile is beyond me. I am guessing the cams are to exploit the new stiffer crankcases for your race engine you have made.

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Originally Posted by olderdan

Tony I am following this project with interest, the mechanical process of cam grinding I understand but designing the desired profile is beyond me. I am guessing the cams are to exploit the new stiffer crankcases for your race engine you have made.

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Alan,

I knew this would capture your attention. Grinding with a motorcycle content, how could it not?

I have written some software to synthesise cam profiles given certain inputs and limits. I have also built a setup for testing cams and viewing in slow motion with a triggered strobe light. This is basically an engine shell with a stripped and balanced crank to drive a cam under test. This is belt driven by a 6 hp motor. I have a dummy cylinder with viewing ports etc. Anyway, I want to made cams to the profile calculated by my synthesis software in order to validate (or not) the software. Well the software is only the messenger, the real test is whether I know what I am doing. This may be of interest https://www.youtube.com/playlist?lis...SvlfD6C_oAHYK3

That is reason no.1 for making the cam grinder, no.2 is as you surmise for my own race bikes. There is a no.3 reason. I have a mate down under who wants to make cams for ancient JAPs, these are not available in the average hardware shop. He has a cylindrical grinder that he wants convert along the lines that I plan with my lathe.

For some time I have been thinking about converting my lathe to linear rails on the X axis but it always seemed like too much work until a couple of nights ago when I saw that it could be done very easily as described in the video. I have the slides on order but they are not due until between 27/12 and 19/01. Impatience got the better of me this morning and I did the modifications to the cross slide from the old larger lathe to take the slides. I was able to test fitting and function because I have the same type of slides, only longer, for another project. There is not much more that I can do now until the new slides arrive. There is some work to do on the saddle of the lathe but that would put the lathe out of action, so that also has to wait for the slides. Here are some pix of this morning's work.

Attachment 46751 Attachment 46752 Click for full size.

and some of the cam test device

Attachment 46754 Attachment 46755

Part 2 is here https://www.homemadetools.net/forum/...art-2-a-100017

Im gladd your still at it tony!! I had thought about doing this but that will never happen. I sold off my old bug, but still have the aftermerket engines (only 1 small distributor drive vw part & 2 vw keys are used) selling the car wasent a issue as I had planed on getting a dragster for my engines...well the local track got sold to a insurance company to use for a parking lot for crashed cars so...Im officaly done racing. but I still have my fun little turbo GM roadster daily driver. even though Im not a GM fan at all. Keep up the great innovations!!

Part 2

https://www.youtube.com/watch?v=yXm4Sj3OxGY

Looking forward to seeing this in action. What is your chosen material for the cams and heat treatment possibly nitrided?. I was spoilt in my employment as we had our own nitride shop and I used it often as it does not distort the parts.

Quote:

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Originally Posted by marksbug

I'm glad you're still at it Tony!!

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I'm only 80 so I intend to be at it for a good while longer yet.

Quote:

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Originally Posted by olderdan

Looking forward to seeing this in action. What is your chosen material for the cams and heat treatment possibly nitrided?. I was spoilt in my employment as we had our own nitride shop and I used it often as it does not distort the parts.

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I have not decided yet but I am leaning towards an hard facing alloy. Megacycle in the US use that on their cams. I have used this in the past but now there are all sorts of DLC and other coatings available that I will look into. Firstly I will have to convince myself that I can make cams good enough to warrant going further. I have, for a long time, been considering buying or making an HT oven. I even bought some A1 heating wire.

Here is an example of a test cam from 4140 using the X&Y movements on a CNC Bridgeport mill. It measured up fine and I think that my current endeavors should be even better.

Attachment 46838 Attachment 46839 Click for full size.

Part 3 is is now available.

https://youtu.be/waKfJA1Wic8

2025 update. Well it is about 18 months since I fitted the linear rails and they have been tested well both for grinding and lots of turning. I am so pleased with the ruggedness and precision that I am considering doing similar to the Z axis. The bed of my lathe is of an open design, as most are, which means that it is rather flexible, just varying the tension on the mounting bolts is enough to twist the bed. It would seem pointless to add linear rails to such a bed. I have thought about boxing the bed in for more stiffness, it would probably be an order of magnitude stiffer, and filling the void with epoxy granite. This would require great care to maintain near perfect alignment as the extra metal was fitted.

An alternative would be to make a new bed from scratch designed from the start to be torsionally stiff. I doubt that this would be any more work than stiffening the current bed. The headstock and cross slide would probably be the only parts used of the original. Of course I could just buy a larger and stiffer lathe but I am limited for space. Anyway that is not at the top of the todo list. I am currently involved with making a machine tool with 3 axes solid granite slides. Watch this space.

now to add a ball slide to the carriage!!! my enco lathe is horrific, but I do very little nowadays had many more updates to do to it but I looks like I wont be doing them.Ill leave all that up to you. at least it runs extremely quiet, vs as I got it you could barely stay in the shop as it was so much noises comming from the gears.then the carrage travel nut wasent on the same plane as the leadscrew...and so on. when I called enco (MSC) they tottaly disowned it....thier tags, thier colors, thier crate...well I got it the week MSC shut down enco. so they just acted like they never made/sold that junk... never ordered from MSC again. I had been rdering from them for 40 years or more. gotta love big corporation's... they dont give a **** execp for the current order amount...and if it;s paid yet.. they were the parrent co, you would think they would have some sort of quality control on that ****...none at all.