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Member postings for Finn Hammer

Here is a list of all the postings Finn Hammer has made in our forums. Click on a thread name to jump to the thread.

Thread: Restoring a Boxford AUD ll
21/02/2021 13:18:13

All,

I had a word with the tool grinding shop, the manager refused to give a quote, because as he said, maby the guy is able to finish the job in 3 hours, maby it will take him 8, and if I give you a quote on the low side, I am going to pay the difference myself. Very unprofessional, since it means that the price would vary between 3000DKr and 8000DKr (300-800pounds sterling).

That's potentially 3 times what I payed for the lathe in the first place.

Since the steel I made the nose off is already much harder than the steel the scroll chucks are made of, I decided to cansel the hardening and grinding, and instead rely on a turned finish.

Not bad at all, the nose is now turned in situ, and thus there is no runout at all.

What you will see here is a Boxford that thinks it is a Weiler, which is very far from reality, so I guess it is a very sad thing indeed, but I am happy, so who cares.

Image with the old Pratt and Burnered 130mm chuck:

oldchuck.jpg

Not a pretty sight

here is the new DIN55027 short taper nose

noseinplace.jpg

and here is the new Zentra 160mm chuck in place

zentrainplace.jpg

I like this, because it gives me the opportunity to quickly change from 3 jaw to 4 jaw to faceplate, as I originally intended.

Cheers, Finn Hammer

10/02/2021 07:37:45

So far so good, the new spindle nose is now a reality in hardware, turned out from 34CrNiMo6, a tough variety of the steels.
Next step is a trip to the hardening shop, and next again to the grinding shop.

I will not do any of those 2 operations, they require specialist treatment for the best result.

Soon, I can put the new chucks up and start to turn out parts.

img_20210210_081558.jpg

Cheers, Finn hammer

05/01/2021 15:00:08

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.

img_20210105_154826.jpg

The belt that I have is a disaster, however:

img_20210105_154713.jpg

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.
What do you guys do????

I have just talked to a distributor who sells these belts,:

https://www.fecconsulting.dk/kileremme/accu-link-kileremme/megadyne-accu-link-kilerem-profil-a.html

And I have no doubt that it will function exedingly well, but the smallest amount I can get is 7.6 meters, enough for 5 lathes. Anyone in for a group buy, one belt at 1.5 meter would cost 35€ ex. shipping.

Cheers, Finn Hammer

Edited By Finn Hammer on 05/01/2021 15:08:04

Edited By Finn Hammer on 05/01/2021 15:09:37

28/11/2020 08:32:40

All:

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.

Old Mart:

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 .

Niels:

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

Thread: Lathe improvements?
27/11/2020 14:52:44

Thanks Niels,

That link to the gears merchant is very nice

Cheers, Finn Hammer

Posted by Niels Abildgaard on 16/05/2019 15:21:49:

Cheap gears

The original spindle gear is 40 teeth module one and leadscrew 80 teeth.

Thread: Restoring a Boxford AUD ll
27/11/2020 13:00:19

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:

contactor.jpg

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.

img_20201121_134342.jpg

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:

wirefwdrev.jpg

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:

55027n?se.jpg

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.

n?se55027 short.jpg

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.

27/11/2020 13:00:09

All,

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.

img_20200925_114326.jpg

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.

img_20201121_134504.jpg

I sealed it off with a aluminium plate

img_20201121_134610.jpg

And that should take care of an otherwise annoying cleaning task.

img_20201127_091607.jpg

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.

img_20201120_190818.jpg

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.

img_20201121_134333.jpg

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