Myford QC Gearbox Project.

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awemawson:
Yes mine arrived as well. Did you notice the 20% off coupon on the box ?

Pete W.:
Hi there, all,

--- Quote from: awemawson on February 04, 2014, 04:22:25 PM ---Yes mine arrived as well. Did you notice the 20% off coupon on the box ?

--- End quote ---

No, Andrew, actually I didn't. It wouldn't matter if I had, my piggy-bank for toys has been sealed for the foreseeable future! :( :( :(

Well the Postman delivered a few 5/16" BSF taps yesterday but I didn't get to use them until this afternoon.

Here's a photo (staged after the event) showing the letter 'G' drill completing the tapping size hole:

Next, starting the taper tap in the left-hand lug:

That one called for careful coordination between pulling on the head-stock drive belt to turn the tap and advancing the tail-stock to push the saddle & casting towards the tap. I followed with the second and plug taps free-hand. Then I threaded a taper nut-tap through the left-hand lug, clamped its shank in the drill chuck and presented it to the right-hand lug, like so:

Once that tap had started in the hole, I removed the casting from the lathe and finished tapping that hole by hand on the bench and followed it up with a plug nut-tap. Here's a photo of that stage (sorry about the fuzzy picture):

Then I did a trial assembly of the gear cover, back-plate, hinge-screws and lock-nuts:

It's not perfect but I think, with a bit more adjustment in situ, it'll do.

I realise that some readers will think this has all been simple stuff and why am I describing it. Well, the big theme of this stage of the project has been holding an awkward shaped casting and I've achieved that using simple improvised materials - maybe that will encourage someone and help with their project.

The next operation on the gear cover is to drill and tap the 2 BA hole for the spring clip that holds it in the closed position. I still don't have the clip to hand so I'm having to set the gear cover aside for a while.

So I'm turning my attention to actually attaching the gearbox to the lathe. The first step in that process is to drill and tap the two holes in the lathe bed to take the 1/4" BSF gearbox fixing screws, my ML7 is too early to have had those holes drilled and tapped in the Beeston Myford factory. The third gearbox mounting screw fits into the lower of the two tapped holes used by the left-hand lead-screw bearing. Here's a photo:

I was able (long, long ago) to buy a drilling jig from Beeston Myford, it's the top one in this photo:

The 'official' procedure, according to Beeston Myford's Instructions for fitting the gearbox, is to first remove the two head-stock push-screws (they're the ones whose slotted ends you can see in the photo) and attach the drill jig using two 1/4" BSF cap-head screws through the outermost holes in the jig. Then you drill two 1/4" BSF tapping-size holes into the lathe bed, using the jig's other two holes as a guide. Then, you remove the jig and open out the two inner holes to 1/4" diameter, remount the jig and tap the bed holes 1/4" BSF using the opened-out holes to guide the tap. The jig can then be removed and the head-stock push-screws replaced.
However, the jig can't be re-used.

For some reason I now can't recall, I wasn't happy with that procedure, so I reproduced the jig's holes in a new piece of material. I then turned the new piece end-over and spotted through another pair of holes - fortunately, they all happen to be spaced in a way that avoids hole positions clashing. I then opened up the last pair of holes to 1/4" BSF clearance size - N.B. that's bigger than 1/4", the tap cuts with clearance at the thread crests.
I stamped up the holes, 'F' for fixing, 'D' for drilling and 'T' for tapping. The amended design jig is the lower one in the photo. They look like brass in the photo - that's a trick of the light, they're actually both mild steel.
The stampings don't show in the photo, partly because I cleverly arranged the over-printing to hide some of them! :ddb: :ddb: :ddb:
So, I've got a drilling-jig that can be re-used. Roll-up, roll-up, get your ML7 lathe beds drilled and tapped 'ere', the line forms on the left! Er, NO! :lol: :lol: :lol:

That lathe sure looks grubby in the photo. Someone else's post here on Mad Modders mentioned using sugar soap to get rid of the oily stains - maybe I'll try it.

Pete W.:
Hi there, all,

I managed to grab an hour or so in the workshop this afternoon and drilled and tapped the holes in the ML7 bed that support the top of the QC gearbox. I summarised the procedure in my previous post so I won't repeat it all, just a few words with each photo.

Here is the jig, mounted to the lathe bed in the drilling position. I've included the drill-bit in the photo but omitted the drill because I couldn't support the drill and handle the camera at the same time (no room for my lovely but shy assistant, in any case, she was busy elsewhere!). I'm sorry about the poor focus - the camera was having a bad day! The bit of masking tape round the shank of the drill bit tells me when the depth of the hole gets to Beeston Myford's specified maximum depth, i.e. 0.625". It's a solid carbide, stub-length drill, bought specifically for this job.

The next photo shows the jig turned end-over-end to the tapping position and the tapping in progress. I hi-jacked my lovely but shy assistant's aerosol of 'canned air', complete with snorkel tube', to blow out the swarf. (She's an MS-Windows nerd and I'm an occasional computer widower! :D :D :D ) As the lathe bed is cast iron, I drilled and tapped dry (but with care). The taps are a brand new HSS set, again bought specifically for this job.
I wonder whether this operation would be feasible on an ML7 with an induction hardened bed? :scratch: :scratch: :scratch:

Finally, here is the view with the jig removed, a couple of cap-head screws in the new tapped holes and the head-stock push screws returned to their holes. I took care to label them on removal and to replace each in the hole it came from. By comparing the orientation of the screw slots in this photo with those in the photo in the previous post, you can judge how well they went back into their original position.

Well, that's probably all simple and basic stuff but I make no apologies - it's just a joy to me to be making progress.

The next instalment is to clean and critically examine the lead-screw and compare it with one of gear-box length I have in stock. I'll use the one with the least worn thread but if that is the original, I'll have to shorten it. After that, I'll start stripping off the change gear quadrant and back-plate including the tumbler reverse.

awemawson:
Coming along nicely Pete - you'll have that QC box on in no time. You've made quite an investment in tools for that job alone.

I spent the day running about keeping plates spinning on poles :( Power cut just before midnight, sewage system needs power to not over flow, cottages full of guests who you can't tell to cross their legs ! Front gate mains powered, no one can get out or in. UKpowernetworks needed access to their switch gear. Too many things all at once, I need a gin and tonic! Jury rigged 3 kw genny to power the sewage system so that was thumping away all day. Unscrewed gate actuator so it can be manually opened and wedged it open with 20 kg sack of goose food ! Managed to get one coat of paint on that 4th axis thingy under torch light ! Power back on 6 pm - run around undoing that that had been done, reset half a dozen timeswitches, reboot several brace of pc's and routers - relief - need another g&t.

Pete W.:
Hi there, Andrew,

Thank you for your post. Wow, I think I rather have the day I've had than the one you've had!!!
G&T, hmmm, somewhere in the sideboard here I've got a bottle of some blue stuff that I never get the right circumstances to enjoy. :doh: :doh: :doh:

Back in 1988 I had a spell in the bandage factory and got quite pally with the medical student who used to come and chat to me when his superiors weren't looking. He spoke of something called 'the J-curve'. It's a plot of harm versus alcohol intake and it's called 'the J-curve' because from zero alcohol up to X units, the harm is negative, after that graph crosses the axis and harm rises steeply with increasing intake.
The snag is, nobody would tell me the value of X!! :Doh: :Doh: :Doh:

We had a power glitch this afternoon, just a few seconds as though the supply was switching over from one source to another. I was in the workshop at the time while it was hailing outside - makes quite a noise on the new roof. My lovely but shy assistant was 'at the computer' but didn't notice any glitch, I haven't yet looked at the bedside alarm clock radio, I expect it all wants resetting. :bang: :bang: :bang:

A friend of ours a couple of miles from here lost power at 18:00 last night and it was still off at 10:30 this morning. Like you, they have an electric gate and were to go to a wedding up around the M25. He did manage to get their car out but he has some kit that relies on UPS back-up and all the UPS batteries had run right down. They are currently on our kitchen floor, hopefully recharging. Trouble is, the chargers he brought in with the batteries only manage 600 mA so I doubt whether they'll put much of a charge in in the time available. They're gel-electrolyte batteries and need a constant voltage charger. I'm going to suggest to him that he gets whatever sort of a charger folks use with those 'pavement buggies', apparently they'll recharge the buggy battery overnight.

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