Time Machine - Bell Punch Company - PLUS model T - Vintage Time Adding Machine - Retrotech

In this retrotech video we're looking at a PLUS model T adding machine, made in the 1960s by the Bell Punch Company (Bell Punch also owned the Sumlock brand of machines and latterly bought the uk rights to the comptometer name from Felt and Tarrant).
Before electronics took over, calculators and adding machines were entirely mechanical - there were numerous different types such as pinwheel calculators and comptometers - the PLUS Adder works in more or less the same way as a comptometer. This particular machine is specifically for adding time so it has hours and minutes on the display. Other models were available for sterling currency, decimal and even some for adding imperial weights.
You can see my video showing a Muldivo Mentor Pinwheel Calculator here:
• Retro Tech - Muldivo M...
or my video showing a Monroe LN160X mechanical calculator here:
• Retro Tech, Monroe LN1...
If you want to know more about the history of these machines, Jaap Scherphuis has a very good website and also a KZbin channel (links below).
Jaap's website: www.jaapsch.net/mechcalc/inde...
Jaap's KZbin channel: / jaapsch2
Intro Music
"As Yet Untitled"
by GrumpyTim (available to download from GrumpyTim's Bandcamp page)
grumpytim.bandcamp.com/
www.grumpytim.com

[@jaapsch2]

I never actually made the connection between the Petters calculator to the Petters of cars and engines. Thanks for the shout-out!

[@GrumpyTim]

You're more than welcome for the shout out - we wouldn't know half as much if it hadn't been for your videos and website. I had to double and triple check that it was the same Petters but it appears that it is. It's amazing what some of these old companies got up to!!!

[@tomgt007sugden]

I found one of these machines when I was 10 years old. Am sure I still have it

[@GrumpyTim]

Hi Tom, you should dig it out and see if it works - they're a bundle of fun to use.

[@petermurphy5302]

I've just inherited one of these (in exchange for a modest sum on eBay.) Model 309 Plus. Guessing it was for old currency - the smallest unit goes up to 11 before flipping over, oddly. Must say I'm loving it after getting it going with lubrication and gentle coaxing of the keys and arms back to life. Using it is bound to be good for your brain with only numbers up to 5 and the rest down to the user!

[@GrumpyTim]

Excellent Peter, you should have loads of fun with that - ignoring the first three columns for the pence and shillings you can just use it as a normal decimal adding machine - I find that I don't really need to think any more as I input numbers on one of these, although doing subtraction is a little trickier, and I tend to leave that to one of the bigger, full keyboard machines.

[@iosmusicman]

Pretty looking machine. It looks more pink in the thumbnail image.

[@GrumpyTim]

My white balance might not have been very well chosen when I shot that, but it is a strange sort of cream/beige with a slightly pinkish look to it. It's fantastic that they made this machine specifically for calculating time and also another one (well two actually) for calculating weight.

[@BensWorkshop]

That explains why the mechanical adding machine I have is in Petter green.

[@GrumpyTim]

I only found out about the Petter connection in the last month - it's quite exciting and a great link to my other stuff. I love the simplicity of the mechanical calculators - that's not to say that they're basic in design, but when you have one in front of you that won't work (which is nearly always the case when I get them), it doesn't take long to figure out how they should work and therefore what needs fixing. This machine was sticking on the number wheels - old oil that had gone gooey - quick re-oiling and a big clean up and presto, another working machine!!!

[@BensWorkshop]

@@GrumpyTim but have you seen their flying machines?

[@GrumpyTim]

I'd read somewhere that there was a connection with Westland - I had a model of a Westland Lysander as a kid and I assumed it was the same Westland.

[@BensWorkshop]

@@GrumpyTim It is the same Westland yes, started by one of the Petter family I believe.

[@GrumpyTim]

Kind of amazing to be involved in so many interesting things - cool family/company.

[@nickxyzt]

Thank you for this video, it's very instructive. I am thinking about converting a decimal model PLUS to a time model PLUS (with minutes and seconds!) for teaching purposes. Do you think that the front wheels of the 6-base column could be changed from the existing ones in 10-base?

[@GrumpyTim]

Hi nickxyzt, Bell Punch used to offer these machines in loads of different formats, and they even converted old Sterling currency machines to decimal. They did have to swap some of the gears and so they had the correct number of teeth to work in a different base, and that often involved a different axle position. On base 10 machines the front gear axle is a straight rod through the machine, but on other models with mixed bases, there can be other shorter rods (axles) with the side frames drilled in the appropriate position. Also, with the shorter rods, they have to have a retaining clip to stop the rod moving sideways. The number wheels always share the same axle as they always have to show through the viewing window. In theory you could convert one of these machines, so long as you have or can make suitable gear wheels and are happy to strip the machine down to re drill some of the side frames and so on.

[@nickxyzt]

Thank you, this is valuable information. I will do my best with the conversion, and if I will succeed (hopefully) I will also post a message here.

[@GrumpyTim]

Cool, I'd like to see how you get on.

[@andromedaturnbull3512]

The reason why the seconds are shown as minute fractions is because it was intended for billing and timesheet tasks where a per-minute rate was charged, say for example for audio transcription. It remains the case that audiotyping is charged for per minute in the original recording and often when jobs are quoted or billed, a rounded seconds fraction table or a calculator is used to convert the HH:MM:SS time to decimal minutes as this is used to calculate what the client pays; e.g. 01:34:15 = 1h 34.25 minutes x £1.20/min. Therefore showing and handling the fraction entry and result in seconds is not helpful because would require dividing the minute rate by 60 and multiplying by the seconds to work out the price of the remainder (resulting in an awkward small fractions of pence), whereas doing it the other way around requires only that the per minute rate is multiplied by 60 to account for the hours which keeps the result in integers. This was especially important in pre-decimal currency where the price of the fraction represented by the seconds would have been even more of a pain to calculate.

[@GrumpyTim]

Wow, thanks Andromeda Turnbull, that's an excellent explanation, and now you've pointed it out, it makes perfect sense.

[@andromedaturnbull3512]

@@GrumpyTim You're welcome! Glad to be of service. I missed off the final step in the process, I realise. With this method you don't need to calculate the price value of the seconds fraction separately - you just read off the minutes and fraction together ignoring the decimal point, and multiply it by the rate dividing by 100 when writing out the result. Magic! Hope that helps :-)

[@GrumpyTim]

Awesome, again that makes sense. I'm really glad you spotted this video and filled in that gap in my knowledge.

[@offthecuffnstuffreviews178]

Can you help me 🤯I pulled pin out by mistake it took me hour to get the wheel back on 😡 it seems to work but when I reset the first wheel resets to 4 ...my brains is fried ...

[@GrumpyTim]

Hi Keith, those pin type axles are a genius idea for simplicity but also all too easy to pull out a bit by mistake and then everything falls apart. I have an idea why yours is resetting to 4 instead of 0 but I'll need to go and check on a machine later - I'll add another comment once I've checked.

[@offthecuffnstuffreviews178]

@@GrumpyTim Thanks Tim ..look forward to any ideas or thoughts. Keith

[@GrumpyTim]

Hi Keith, I've just had a look at the Plus model T - assuming yours is a similar age there should be some plastic gears at the bottom front with an intermediate gear between them and the number wheel - if I remember correctly the older models had metal gears but apart from that the operation is the same. It's those bottom front gears that index where the number wheel stops - there's a pair of bottom front gears for each column, with a spring between - the spring returns the wheel to zero when you press the reset lever. The bottom front gears can rest in two different positions because they have twice as many teeth as the number wheel - to make it easier to see, enter numbers in that column until the left bottom front gear has it's pin at the front and then press the reset lever. The two pins should now rest against each other with the right hand one above the left hand one. At this point the number wheel should be at zero - if you move that number wheel upwards with your finger you'll see the two pins move apart and when you release the number wheel they'll spring back together. If everything appears to be as I described it, then I think it's only the position of the number wheel in relation to the intermediate gear that's wrong. To adjust this you'll need to carefully withdraw the pin just enough to free up the number wheel, lift the number wheel up just enough to disengage it from the intermediate gear and rotate the number wheel until it reads zero, then lower it back into position and re insert the pin. You might be able to make it easier by inserting a fine pin (the kind of thing you'd use for sewing) as you withdraw the main axle pin - that might just allow you to angle the dressmaking pin enough to get the number wheel to disengage from the intermediate gear so you can turn the numbers back to zero, then re angle the dressmaking pin to lower the wheel back in line with the axle pin and push the axle pin back into place. Just a side note, probably no help here, but there is a spare axle pin on these machines - it can really help if you have one that needs cleaning or lubricating - The Green felt material that sits beneath the keys and on top of the mechanism to stop dirt getting in is held in place with some bent bits of wire - these are located at the rear by a pin - this is the same material and dimension as the axle pins and can easily be removed. Once removed, this pin can be used to push out any of the axle pins without all the bits falling off. Hope this helps a little bit.

[@GrumpyTim]

Hi Keith, I've just been working on another of these, I'd forgotten that the older versions don't have the spare pin at the back to hold down the felt bits, so that bit of my reply might not have made any sense. There is still a pin at the bottom front that just holds some of the frame together - I successfully removed this one to use as a substitute pin/axle while I cleaned old sticky oil off the actual pin/axle.

[@offthecuffnstuffreviews178]

Hi Tim , thanks for the help the spare axel did work .. I did send you a reply but it seems to have gone missing.. I did get it all back together and it all seemed to work ! But when putting it together I did break the Number wheel so had to glue it back together .. As I said I got it all back together in the end all seemed fine apart from when the first wheel was on Number 8 .. it would not reset ! I did send you another email asking anymore ideas but that looks like it was lost.. It took so long to get the cog , number wheel & washer together..the 1st and then 2nd time I found it hard to find the courage to go for a 3rd time .lol .. I left it until the next morning with a fresh head and looked at it logically it was resetting from 7 & 9 but not 8.. so before I took it all apart again I looked at where I had glued the wheel ! And there it was ! The opposite side to the 8 was where I glued it and a bead of glue was on the side of wheel and rubbing against the plastic cog .. thanks again Tim ... Keith.