Member postings for Adrian R2

Buy slightly larger and wrap some suitable shimstock around the shaft, leaving a gap for the key?

Anyone had dealings with Hemingway recently? Over the last week or so I've filled in their web form, emailed and telephoned but no reply to any of these as of yet. No particular hurry, but should I wait for them to respond or keep badgering?

(I want to know if the predrilled indexing gear for the Thomas VDH is available separately from the kit)

Adrian

What make is your mill? You seem to get very good results from it, having that many gears mesh properly must be satisfying.

Ball with a hole in it so it can slide smoothly on a piece of string, pin the ends of the string to the each end of the mould with sticks, ensure ball moves smoothly across whole surface when slid back and forth on the string?

A point on elipse is defined as having constant sum of distances to the ends, this works in 3d as well as 2d.

Will need some experimentation with size of ball to see what works best.

I think that will have the same problem as I found for my lathe - although correct form exists the insert will be too big to fit in the internal diameter. I got some suggestions as to other sources for tooling, see this thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=169205

Find some lengths of ground steel rod with nice perpendicular ends, or perhaps the blunt ends of a decent set of drill bits, poke them in the taper and then plot the various depths and diameters on a piece of paper*; do this enough times until you get a straight line then calculate the angle and big and little end sizes.

Some common and less common taper dimensions on Wikipedia here to compare with, a similar exercise for my lathe spindle identified it as Brown & Sharpe No 6.

https://en.wikipedia.org/wiki/Machine_taper

*or spreadsheet and chart if you are digitially minded.

Photo of cross slide. As it's all steel with no castings I suppose it could have been fabricated from stock and not be from anything, but if anyone does happen to recognise it please shout.

Research status: Tracy Tools have a long 5/8-8 RH ACME tap and Noggin End have square bronze bar (PB102) which if sawn accurately might fit nicely without needing much machining, other than the boss.

Edited By Adrian R2 on 23/11/2020 14:01:20

Hopefully sketch is attached to previous post - can you see it?

I would love to know what the cross slide is actually from, looks like someone has made a tidy job of milling the top of the original carriage flat and then bolted this one on. I don't have a picture of it assembled to hand, will take one over the weekend but this is the lower part in place with nut and leadscrew refitted.

I did consider going metric (I have an ARC digital scale on it anyway) but decided not to confuse any future keepers further.

OK, so forget about inserts, either not available or prohibitively expensive.

Not sure I'm up to grinding an accurate tool, but I might be able to grind a near-ish tool and then finish with a tap. There's a tandem tap on amazon that looks good, but unf. from a US seller which doubles the price.

The delrin idea is interesting, I can see that working for CNC with many light cuts but whether it would stand up to my ham fisted lathe turning is another matter.

This is what I'd like to make, and to add to the fun I need to make it on the lathe that it will be used for.

Edited By Adrian R2 on 20/11/2020 15:47:57

Is it possible to insert tooling to cut an internal 5/8 ACME thread (8 TPI, and RH)? Web searches throw up options from e.g. Cutwell in 16mm form factor which is going to be too big to fit inside, surely, unless I have misunderstood the nomenclature?

This is for the unidentified cross slide that is fitted to my ancient Barnes lathe. The original screw + very worn nut appear to be square which I doubt I could make, but I have a new length of ACME threaded rod available.

RDG and Tracy offer hand taps, but I'm assuming I'd have to start it off somehow before using one of these, so wondering whether an insert tool is available that would do the job in one.

I've had better results by drilling slightly undersize first (e.g. 5mm in this case), followed by a check to see how it turned out and then a light cut with the size I actually want for the tap. This with cheap drills and an ancient drill press.

I think I'd cheat if possible and buy something that has the correct internal taper, mount it on an existing taper tool that I could hold in the 4 jaw chuck and clock to be sure it is concentric and then see whether I could machine the odd size taper on the outside. The bought in something might be case hardened so may need a bit of a preparatory grinding to soften it up before lathe work starts.

Logic is that this saves a bit of work and gets you a professionally hardened taper where you most need it.

Good point Bill. Mine was the PWSA 20-Li-B3 which is variable speed and uses the current X-team 20V battery.

re: Electronics, you could try looking for an obsolete cordless drill on ebay/gumtree/preloved whatever and pinch the controller from that. I bought one earlier in the year for a fiver incl. p&p as I wanted a battery motor for a project - was nominally 18v but runs OK on 20v (voltage difference is mostly marketing I think).

Edit - Tony, mine was about 20 months old - no return to store offered but as above they did honour the 3 year and paid for return shipping.

Edited By Adrian R2 on 05/11/2020 10:26:54

Bill - I have just returned my grinder under warranty as I'd used it enough to wear out the spindle bearing. After a couple of emails to customer services with proof of purchase, serial number etc. they emailed a pre-paid UPS label to send it off to Germany, and after inspection have promised me a new one to arrive in January which I assume is when the next batch will be manufactured. They didn't offer me a refund up front or I would have gone for that and attempted DIY repair.

Bazyle - with the 4Ah battery it runs a de-rusting wire wheel for long enough to remind me that I don't like holding on to vibrating tools - I'm ready to stop when it is. Similar with my cordless hedge trimmer, having to recharge batteries stops you overdoing it and ending up with neck and shoulder pains the next day.

Edit - "Do they fit?" - not as supplied as the guard covers top and bottom of the disc and generally gets in the way, however I used a cutting disc to weaken the spot welds holding the two parts of the guard together and discarded the lower bit after which it is much more useful.

Edited By Adrian R2 on 05/11/2020 09:48:38

Would some plumbers freeze spray help? Just a thought, I've not tried it on this application but it does sometimes work on things that you can't apply force or heat to.

Second the extend/retract a few times advice. I'll add that the working pressures in a tractor hydraulic system are huge (e.g. 2500psi), and any attempt to bleed them would be potentially hazardous. Resist the temptation to loosen any fittings when the engine is running or if there is any residual load on the system. When I park a machine up I try to work all the levers after switch off to depressurise it.

Ah, I see now. I'd assume differential between the axles but clearly not. Coming on well, keep at it.

I'm trying to imagine the gear setup here - presumably the two black marked bosses at the front are cross shafts for the actual gear change, then the blue one is an idler and the differential goes under one of the humps? If so what's the second, a transmission brake perhaps?

I converted my ancient lathe to 3 phase with an inverter drive a few years back. Didn't get as far as rigging up the pendant but it has made the machine much nicer to operate, only minor quibble being a bit of static hiss on the radio which I haven't managed to suppress.

On the DC side when my kids were smaller and I converted a Sonic 7 (think half scale Lotus 7) from petrol to electric using the drivetrain from an off road mobility scooter - bonus there was that the drive controller incorporates lots of safety features e.g. handles full forward to full reverse gracefully.

So either could work for the UPT if a motor is available in suitable size. I realised I made a typo above, the GHT book says 1/12th hp motor so in metric we are only talking 75W or thereabouts. I would only anticipate using this device for small drills, say up to 5mm so controllability will be more important than oomph.

Indeed. I made the missing pulleys and mounting block over the weekend and tried the Bodine motor. Not a very good test as I was using a piece of string as a drive belt (proper one in post) but it starts with quite a jerk so DC may be the way to go to get variable speed and soft start if no other reason.