|Finn Hammer||27/11/2020 13:00:09|
5 forum posts
My name is Finn Hammer, I am a toolmaker by trade, finished my apprenticeship in 1972, but the last 32 years I have made my way as a Chiropodist. As a side business, I construct Tesla Coils.
I recently bought a Boxford AUD ll lathe, and I thought my considerations during the rebuild would fit well into this forum.
The lathe had been dismantled by the previous owner, and this should prove beneficial to me, since I could handle it on my own.
Here you see it on the trailer, just arrived.
There are a couple of goofs on the bed of a boxford, the first is the pit for swarf and coolant right under the parking space of the tailstock, at the far end of the bed.
I sealed it off with a aluminium plate
And that should take care of an otherwise annoying cleaning task.
The other goof concerns the tightening and loosening of the clamping bolt at the front of the spindlestock. Even with a special spanner this is an inconvenient task. However, by drilling a hole in the bed casting, and exchanging the hexagon bolt with an allen bolt, the key can be inserted from below. Much easier!
I sent the stand to sand blasting and priming, and this saved me a lot of time and effort, and produced a wonderfull finish.
You can see that I added a VFD to the machine, a 4kW unit, which can stop the motor in ¼ of a secont without going into overvolt tripping. This VFD has an annoyingly loud fan, which got replaced.
|Finn Hammer||27/11/2020 13:00:19|
5 forum posts
The stock contactor was always noisy, hummm, buzzzz, you get the picture, so out it went, and here is the wiring diagram for the standard 4 pole contactor I replaced it with.
I am sensitive to sound. here is the wiring diagram of the new contactor:
The box with stop, fwd. and rev. buttons contains some relay logic, to keep the VFD turned on by a press on a button, and also disable the opposite button.
It also contains the option of adding an external stop switch, which can come in handy, when threading into a bottom hole.
The wiring diagram is here:
There is one decision coming up rapidly now, choise of spindle nose.
If I keep the stock 1-1/2"x 8 TPI nose, I will have to machine 3 backplates for the tooling I intend to purchase: a 160mm scroll chusk, a 200mm 4jaw independent chuck and a faceplate. (the latter will be waterjet cut and mounted on a ready made adapter plate for the spindle nose of my choise, the ISO 902-3/DIN 55027. I bought the standard PDF.
My main concern here is the extra added overhang that will inevitable be the result of this setup.
If I turn the adaptor according to the standard, this will be the outcome, and I even have to trim the labyrinth faceplate to make way for the 3 nuts:
I don't feel too comfortable with adding almost 25mm of extra overhang, so I propose to slim the adapter slightly:
The flange is 20mm thick, which seems reasonable on a spindle with a 40mm bore, but the Boxford is tiny in that conparison, so I will trim 8 mm off the flange, to make it 12mm thich
The bayonet plate is 6mm, I will make it 5mm instead.
Lastly, by trimming the nuts down to 8mm length instead of the original 12, I will reduce the extra added overhang by 13mm.
I am not at all sure this will matter, seems like I am rapidly entering the territory af the diminishing returns, I will see what you guys have to say about this.
|Gerard O'Toole||27/11/2020 15:23:50|
|96 forum posts|
I am watching with interest, having recently bought a Model A Boxford.
It all looks very good.
5698 forum posts
Did you notice that in the 'lathe improvements' thread Niels was initially thinking of modifications to a Boxford spindle?
|old mart||27/11/2020 20:01:54|
|2472 forum posts|
There may be more than one drawback to changing the standard backplate for your ISO/DIN adaptor. When you produce the 1 1/2" register and thread in the adaptor and fit it to the spindle, the front will require machining to get it to run true. All backplates fitted to threaded spindles are machined in situ. The only advantage of your adaptor that I can see is being able during assembly, to provide a positive locking to the thread to ensure the lathe is safe to use in reverse. The locking could be permanent as long as it did not interfere with removal of the spindle from the headstock.
160MM chucks are much bigger than 5" / 125mm chucks, in weight as well as length. There will be a sacrifice in overall length between centres as well as a small stiffness loss.
|not done it yet||28/11/2020 00:33:32|
|5382 forum posts|
Boxford? Screwed-on chuck? You are going to arrest the spindle from high speed, to rest, in a 1/4 second? I do hope you have nothing screwed to the spindle, or it may well unscrew in about the same time, or less. Wear your toe-tectors and don’t stand in line with the workpiece/chuck is my advice if you try that trick too often!
Seriously - don’t do it. It is dangerous.
|Niels Abildgaard||28/11/2020 05:43:47|
|368 forum posts|
My chinese sewing machine motor on a 180 lathe unscrewed a 100mm chuck and I will never even think of screwed on lathe workholding tools.
Next time an impoverished and starved Boxford follows me home I will make it a new spindle and be my fifth .
|Finn Hammer||28/11/2020 08:32:40|
5 forum posts
I thank you for your safety considerations regarding the possible unscrewing of the chuck while reversing the spindle, or by simply bringing it to an abrupt stop.
And please excuse me for not stating the obvious: That the DIN 55027 adapter will of course be secured to the spindle with locktite.
You say that the 160mm scroll chuck is much bigger in length.
Hardly, I would say: The standard P&B 130mm chuck measures 76mm from backplate seating face to the front face of the chuck, whereas the total length of the Zentra chuck I am going to buy is only 68 mm. This places the front face of both options on the same line, therefore no recuction in stiffness .
I have seen your spindle creations, and they are definately a step in the right direction, however:
There seems to be no feedback to the leadscrew, thus no automatic feed, and no threading ability.
What standard do you adhere to for the spindle nose?
And finally, although the back gear is inherently noisy, I think I might need it for heavy duty coil winding.
Cheers, Finn Hammer
|Finn Hammer||05/01/2021 15:00:08|
5 forum posts
The Boxford is now closer to being operationable, spindle is in, and pre-preloaded, a test run will show if it shows a proper temperature rise when running.
This belt keeps getting longer by the minute, and I wonder what you guys do, it is a hard job to join it inside the motor cage of the support, and I have to take links out all the time. No option to tighten it either.
Edited By Finn Hammer on 05/01/2021 15:08:04
Edited By Finn Hammer on 05/01/2021 15:09:37
|113 forum posts|
You can buy those link belts on eBay - no need to purchase 7.6m
They cost about £18 per metre.
I bought some for my Denford lathe and they work just fine.
|Alan Charleston||06/01/2021 05:16:27|
|101 forum posts|
I bought a new T Link drive belt when I restored my AUD from here:
Tony quotes 60 pounds for a 1.4 meter length which is required for a Boxford. This seems a lot more expensive than the 18 pounds/meter from eBay but on the other hand, mine hasn't stretched since I put it in a couple of years ago.
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