Member postings for Andrew Moyes 1

If it slows down when drilling, on the Super 7 it can also mean the adjustment of the front taper bearing is not correct. It could be that the front bearing is taking the end thrust which it's not intended to do. The thrust should be taken on the back (ball) bearing. The manual describes the adjustment procedure.

Thank, all, for the info. Tug - that's a kind offer re the manual but I have the leaflet that was supplied with the head. It covers user instructions, diagram, spare parts etc. Studying the exploded view of its inside has convinced me to leave it well alone!

Andrew

Thanks Andrew. That's reassuring to know. It must be a design feature then.

Andrew

I have recently acquired a Tapmatic 30x tapping head, supposedly having had only light usage. I am surprised at the amount of side play in the spindle, somewhere around 20-25 thou. Can someone who has owned a new head tell me if this is normal, to allow the spindle to align itself with the hole? Or is mine more worn than I was led to believe? Thanks.

Andrew

Bo'sun - Rotagrip in Birmingham sell the Vertex collets.

Here is the evidence. It's a nice sliding fit on 3/4" stock.

Look up the thread 'QCTP mounting on the Myford S7' and you will see some solutions.

I have a Vertex set of metric ER32 collets. They are more expensive than the run of the mill Chinese collets and are supposed to be of better quality. The 19-18 collet is also marked 3/4" so they are not worried about the extra 0.05mm. Opening it up that extra small amount will stress the collet less than closing down a 20mm collet almost a full millimetre but in theory that should be okay too.

I have a '2MT to 2MT adapter' for my Myford. I find it very useful for some operations such as tapping or using small, and therefore short, drills. I bought it from Chronos. I didn't have great expectations for accuracy as it's almost certainly Chinese but was pleasantly surprised. The runout is about a thou. The resistance to lateral forces is not great, as you might expect, but it could support light turning eg clockmaking. It seems fine for axial loads though.

Andrew

I looked up the construction notes supplied with the Mk1 machine. Arnold Throp said 'A 1/3hp motor is quite adequate for all the work a machine of this kind will normally be expected to do.'

Andrew

Edited By Andrew Moyes 1 on 01/05/2021 22:52:00

The machine was in a generally clapped out condition so I decided to give it a top-to-bottom overhaul, leaving no stone unturned. While I had the motor apart, I changed the bearings, checked the centrifugal switch, stripped off the unsightly hand painting, and resprayed it. The flat belt has been ditched and replaced by poly-vee.

The hexslides are next. Where the slides have worn, I will cut some relief slots across the fixed bars at the ends of travel. This will allow the bow to overrun into the slots (as on loco slide bars), then I'll re-shim the bow.

Hi Chris. Having just stripped down the 1/6hp Hoover motor on my Kennedy hacksaw, I can confirm they are definitely ball bearings and it should be grease not oil. The bearings are shielded on their inner sides (to protect from dirt and retain the grease) but open on the outer sides so they can be regreased.

I have replaced the bearings in mine and tried to obtain bearings with a single shield but without luck. The original bearings are 6203-Z. I think the suffix Z means one shield and ZZ or 2Z means two shields. Although I carefully ordered suffix Z, they came with two shields. Rather than trying to prise out one shield, I decided to fit them as they were so it is now a 'lubricated for life' motor, a nice euphemism meaning they can't be regreased. They will see me out.

Andrew

Thank you all for your thoughts. You have persuaded me to take the easy route and use ground silver steel. That’s on order together with the Oilite bushes.

It’s interesting to note that while the original ¾” dia mild steel crankshaft and bronze bushes are badly worn, the much smaller 3/8” dia crankpin which is hardened and runs directly in the cast iron connecting rod is perfect with no play.

I have replaced the motor bearings with SKF ballraces and converted the flat belt drive to poly-vee. The saw should be a useful addition to the workshop when finished.

Duncan, all the commercial shafting I have seen is metric. Altering the machine casting and pulley to take a 20mm metric shaft and bushes instead of 3/4" is another option but more work.

Re the suggestion to use unhardened EN8, the original unhardened shaft has worn badly, hence why I wanted to do something better. That seemed a good idea at the time but maybe I should just do that and replace it again if and when it wears.

If I were to use a high-carbon steel instead of carburising, to what colour would you suggest the shaft be tempered?

Andrew

I too am restoring an old Kennedy power hacksaw and by luck I stumbled across this thread. I have exactly the same problem of a worn shaft and bushings. On mine, the shaft is unhardened. I intend to fit new Oilite bushes and would like to upgrade to a hardened shaft, which I believe is advisable when running in bronze. I can’t find any commercial source of ¾” hardened and ground steel. So I thought I would have a go at turning down some EN3B, carburising it using an old tin of Kasenit I have and then grinding it to size on the lathe with my toolpost grinder. I’m wondering how much grinding allowance to leave. It needs to be enough to correct any distortion but not enough to grind through the casehardening. The shaft is only 4.3/4” long and I will plunge the shaft vertically when hardening it to minimise distortion. My gut feeling is about 4 thou but I don’t have any feel for how deep the carburising will be. Any advice will be gratefully received.

The 200ml drip feeder was cheap on ebay but I had to true up the needle point before it would completely cut off the supply. After that, I found the flow easily controllable by observing the drip rate through the little window. I tried cheap Chinese coolant hose but it leaked at the joints so I replaced it with good-quality Loc-line hose made in the USA. The hose holds quite a bit of the oil in its joints so the response to the drip rate can be delayed which is a slight nuisance. At some point, I might replace it by plain clear aquarium hose with a bendy wire down the middle. Apart from those hiccups, I’m well pleased. I can position the drip feeder anywhere within a 100mm radius circle, swing it in towards the tool or out of the way when not needed.

This is my version of an alternative QCTP base. The excellent idea of using a 5” chuck backplate casting was one I first saw on this forum; I don’t claim any originality for it. It was an easy turning job.

Since it is only ever intended to be used with the QCTP, I turned a shallow recess of 35mm diameter to avoid the tendency for the toolpost to shift. It needs much less force on the ball handle now to lock the toolpost firmly in position. I made the base 1/8” lower than the compound so I can use ½” tools if I want.

The improvement in rigidity is marked. That, plus the coolant drip feeder, mean I can now part off confidently using the power cross feed. It achieves the full potential of the big-bore headstock which I felt it lacked before.

My Super 7 has a 1/2" x 10tpi RH Acme thread on the cross slide. I believe the ML7 may be 3/8" X 10tpi. Tracy Tools sell 3/8", 7/16" and 1/2" taps of that form and pitch.

Thanks, all, for your advice. I'll go for green. Taking on board Brian's points, I'll make it a darkened and rather grubby version of GWR green.

Andrew