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Think of it this way - normally when dividing, the pointer indexes around a set number of divisions on the (fixed) dividing plate. With differential indexing, the dividing plate is not fixed but geared to the spindle, so as you index around, the dividing plate moves just a little bit more. In comparison to normal dividing, the pointer (that moves the spindle via it's handle) has moved in absolute terms slightly more. From memory, I think the standard set of gears that comes with a dividing head can all be made on a semi-universal head so you are safe!

@@occasionalmachinist thanks for taking the time to reply,, cheers

I've used it once or twice since making them. Comes in handy.

I must admit I like cutting gears - there is something I find very soothing about it.

Most people don't need differential indexing - I'm doing it for a set that I want to make. The other use is to produce a 127t gear for metric conversions. Other than that, it's pretty esoteric.

Sorry. I tried to explain it as best I could. Think of it as normal indexing but instead of going a fixed number of divisions, you go a number plus 'a bit'. That bit is dictated by the gearing that feeding back.

@@occasionalmachinist after rewatching it twice! I think I get it. Basically if you want to do more than 50 holes or a prime number of holes, then as long as you have the relevant charts and gears you can do it on the say 50 hole plate and the head will compensate?

@@paulrayner4514 More or less! Which division plates you use and the gearing that works requires calculation (but in the tables/ chart). For the 77 tooth gear I was using a plate increment (10 on a 20 hole ring) that would have given me 80 divisions - but because of that gearing, it dropped back to 77.

Traditional texts on cutting gears with a dividing head say to go around once with a light cut to check the divisions - bit like that first skim pass when cutting a thread. Trouble is, that takes time, especially for a larger gear. Centre punching or using a pen or something would take time too. If you think 15 seconds per mark, that's still around 15 to 20 minutes for a gear this size. I haven't got the patience.

I would not recommend it, as the steel wool would likely scratch up the finish. One thing to try is some aluminium foil. Rub that on the surface rust and you may find it removes it. I don't know why - I have wondered whether rubbing the foil strips the oxide layer off and then the raw aluminium in turn strips the oxygen from the rust. However it does work, it seeks to work- you might have to live with a very slight stain - but it's patina right?

@@occasionalmachinist Thank you so much for your thorough answer!

Yes, although I'm lucky as the draw bar is at my eye level, and that's with the mill being on a platform that brings it up around 200mm

@@occasionalmachinist I mostly commented as the pneumatic cylinder for drawbar action and tool change is 99% for machines which do not use the quill function anymore and have disabled it (otherwise the quill will be pushed down when activating the pneumatic cylinder). Using an impact driver that sits above the drawbar and can be lowered and spun either right or left is the solution for manual mills while keeping the quill functionality.

@@joansparky4439 I've seen it done, and for some people it is a great improvement. I think there are even kits available these days. I was told by a toolmaker once that milling with the quill extended causes more wear (better to use it just for drilling), so even those machines with a quill could productively change over.

​@@occasionalmachinist if the quill isn't available for extending while drilling it would need to be done with the head / table .. (I wouldn't mill anything serious with quill extended farther than 1/2 of the large tool taper diameter). The pneumatic systems rely on belleville washers and the quill being locked + wont work on mills with MT taper. So impact driver it is ;-)

I've always been of the understanding that if a tool points say to the right and cuts in that direction, it's a right hand tool. Looking at the tool itself it is a right hand. Looking at it mounted in the lathe, it could be considered left hand. A bit ambiguous...

@@occasionalmachinist I guess we both been in the trade long enough so I can only suggest you do your own research.

You could use Delrin. That was laminated from several pieces of plywood as it was what I had. The wood can be repaired easily if damaged and as you point out the friction between Delrin and metal may be less, but probably not enough to matter much.

No probs.

One of my early efforts, but with some stuff worth seeing again

Short for utility. Circle work is one term for doing burn outs in one, as without something in the back it is light and does them more easily. en.wikipedia.org/wiki/Ute_(vehicle)

Thanks for appreciating it!

I wondered whether anyone would pick up on that...

Good thought if your crossslide can reach that far. I occasionally run the lathe in reverse but usually avoid mentioning it as there are lathes out there with screw on chucks, and running those in reverse can be dangerous.

@@occasionalmachinist the tool would still cut at the front if inverted.

@@marley589 It would - I usually cut at the back with an inverted tool, so misunderstanding on my part. However, the chuck still needs to run in the direction that it unscrews though.

@@occasionalmachinist an inverted standard boring bar could not cut an outside diameter at the back whatever spindle direction you use. It could at the front in reverse though, as my original comment.

@@marley589 Yes, you are right.

No problems.

That's a horizontal milling cutter that has a 90 degree grind on it. If I were using it to mill a flat piece it would put a 90 degree groove in it. I think it came from a box of stuff someone gave me, but eBay could be your friend...

I have a similar view - everything is a spring. It helps a lot when thinking about how things might move, or how they will behave.

6 jaw chucks are a bit of an odd one. I worked in a place where they turned thin wall tube and they helped with that, but with anything more substantial, you can't guarantee all the 6 jaws will be in contact (bit like the 4 jaw scroll chuck from a few months back)

@@occasionalmachinist Absolutely, it always concerns me when I see people using 6 jaw chucks as their STANDARD chuck. Looks good but doesn't mean that it is the right thing to be using. For those that may want to know why.... or TLDR 😀 Its kind of like weight ratings for casters (solid wheels), to use an example that may explain another "oddity". The caster may have a rating of 100kg but 4 of them will have a rating of 300kg, because you can only guarantee that 3 will be contacting the ground. (like a 4 legged stool). If you keep adding more casters the rating shouldn't change because you still can't guarantee more wheels will be carrying the weight, as the wheels (and the ground) don't deform. To get a higher rating total than 3X for a given wheel rating you would need to change to a flexible wheel (e.g. pneumatic) or suspension of some sort so that ground contact can be assumed. Back to chucks - 3 is the best as they must all be in contact - as you have said 4 or more do not GUARANTEE that there are more in contact. However with a THIN walled workpiece, or at least as it gets machined, the workpiece deforms (as you showed). The method of holding determines how much and where it deforms. The extra jaws limit how far it can deform. If the outer surface is already "machined" in some way (ground, bright etc) then all six jaws will be in even contact (or very close) and the deformation will be very limited. An ER collet will be better as there is so little distance between its 6 "jaws" 3 front and back over its 1mm clamping range). A 5C collet has small gaps to its 3 "jaws" - but it only has the front jaws, but due to its limited range (~0.1mm) works. Somewhere in-between I would guess is the Pratt Burnerd collets (3mm range) but narrow jaws. My lathe came with 5C and PB collets - I will be adding ER40 to match the milling machine..... then it will be choices/choices..... 🙄

No problems - the stuff in there is the sort of thing that is learnt by experience and rarely spoken of.

I did - it's the video entitled "Look what the metric system made me do", but I got a couple of comments suggesting making a whole new part was not the easiest way of doing things. This is an explanation of the issues that those ideas may have problems attached to them.

@@occasionalmachinist Ok I get it now, I think. I don't know why your friend wanted to change to a metric in the first place. If it isn't broke, why fix it? As far as everything you said in this video, I agree.

@@opieshomeshop It was originally 20mm but a previous "fix" converted it to ¾" and the bores in the band wheel modified to suit an imperial bearing. That ended up as a failure so this was taking it back to the original specification.

@@ericparsonage7938 I see. Thanks for clearing that up. 👣👣👣👣👣👣👣👣👣👣👣

Thanks.

There are additional videos about the sharpener where I build a copy (others also wanted the drawings, but I had not gone through and checked them, so this was the simplest way). The drawings are scattered through the videos as needed. I did find a couple of errors and some things that I thought could have been done differently/ more efficiently, so that is in there too. A couple of people I know have made them and used them, so it seems to work.

@@occasionalmachinist thanks for the reply, I'm working through the series.

That is the nice thing about a device like this

I've done it, and successfully, but it needs care with heating the steel blank - too hot and the plastic melts out, too cold and it does not form the teeth. If you have an IR contactless thermometer, that could be a great help.

I've had that box for close to 40 years now. Normally there is a piece of paper over the top, but it gets used quite a bit as it is just a nice height for standing.

Don't know how you found that. As it's for a camera, I'll call it a Rosette gear (from Wikipedia)

I'm keen to firm up the hinge as its an experiment, and a bit of a lash up. I may also put some depth on my trusses and try to reduce twist that way. It works as is, so plenty of time for thought. A counterweight or spring might reduce the twist a bit, but I need a dampener really. I'll have to see what devilishly intricate and overly complex solution I can come up with.

Thanks.

Thanks.

Bounce is a problem. I'm still thinking about that one. The boom is usable, but I may need to remake the hinge. Being a welded construction of commercial hinges, it's a little loose.

It takes a bit of geometric thinking, but I work out the circumference of the part and divide by the number of teeth. Because it is a 90 degree tooth, the mid-plane distance between teeth is twice the distance from the mid plane to the bottom of the tooth gullet (or a tooth tip). Knowing that mid plane to bottom gullet distance and the radius, angle= arctan(tooth gullet distance/radius).

@@occasionalmachinist Thanks for that 👍

I've seen articles showing these used back-to-back with different pitches to give a low profile discrete movement rotary table. For example, coarse movement one way then fine movement either forward or backwards gives many more discrete movements.

@@russelldold4827 Interesting idea, although sounds like an added complication that most people would not use. Bit like an epicyclic gear box?

Mill tooling is one of those things where you can continuously ask where do you stop. The collet blocks are a good suggestion, although a bit specialised for starter tooling.

@@occasionalmachinist I agree again. the collet blocks are not a beginners must have. I have been into model engineering for a bit over 60 years, and the gear that is readily available today for the home workshop is fantastic. I think 'where do you stop" depends pretty much on where you are going in the workshop, and expanding the kit of devices serves to improve capability, speed, and sometimes finish of projects. I think that RUclips videos such as yours are really good at introducing newbies ( and oldies) to what is available, and what can be done with it at home. I am continually amazed at how much I depend on the mill. This was very evident earlier in the year when I had an electrical problem that took quite a while to sort out. My first "milling" was on the Myford super 7 with a vertical slide. That largely dealt with my first locomotive, so you don't need to start big. Anyway, it is good to see a workshop video that doesn't assume that you have everything on hand.

It does come in handy. I'm glad I made it.

You are right, and one day I'll finish up the little R/T so I can do that. The only one I have is 8" diameter, and for little things like this, getting it out seems a bit silly some time.

A few bits of the story were edited out, but this is for 3mm thick Al panels, so bending is not a major concern. They are a pretty standard connector so for a one off, I would agree that it was more time consuming, but I expect to have to do one or two of these every few months, so over the next year, I think it will earn it's keep. If I had two plates, I'd also need some way to line them up. The steel is not really hard, just hard enough that I'm not going to accidentally file into the template. A small round file like the one used is relatively inexpensive and I'm only filing the Al till the feel changes, so I don't think I'm damaging the file in a major way. Thanks for asking though - it keeps me honest!

@@occasionalmachinist Much appreciate your feedback, thank you.

Yes - I think the next one that I do will be a 9 pin D - for some reason the 25 pin D connectors don't get used much these days (maybe all those pins that don't do anything...) One thing that in hind sight I should have done was put some cross hairs on the template for more precise positioning. There's always something.

I did think about a punch and die, but I would need a die set to hold them in just the right relationship, and Murphy's law says there will also be panels beyound the throat of the press. This is more low tech but more adaptable too. I try to make clean up as quick as possible, so I tend to have chip trays to collect the majority of the swarf if I can. The one for the mill is new, but the oil quench was done on the cabinet that sits under the drill table - the top is a removable chip tray too.

@@occasionalmachinist A rolling chip tray makes a lot of sense, too. You are always a source of interesting ideas. As far as a punch and die goes, I was thinking the kind with a bolt through the middle joining the two halves and which you use to drive the punch through the work, as opposed to the kind that goes in a press. They may not be as quick or as precise, but they are a lot more versatile! Thanks for sharing your work and your ideas.

@@fxm5715 Might work - the concern here is that the material these cutouts go into is 3mm Al. I'd be a bit concerned that the thickness would either snap bolts or just bog down (the cut out in question was 13.5mm across the flats so a bolt would likely be M6, perhaps M8)

​@@occasionalmachinistUse a piece of urethane as a die. No need to line up the the punch. A couple of example demos on my channel.

@@occasionalmachinist Agreed, 3mm in aluminum is a bit gummy for a punched hole that small, with an imprecise, underpowered punch.