NEW BRITAIN CHAIN MORTISERS

MODEL 2

This is a Model 2 New Britain Chain Mortiser. It likely dates from around 1915.

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This machine has always gotten a lot of use. It will need some work soon but it keeps on going. The large belt drives the chain sprocket arbor. It runs about 3200 rpm. I believe the original rpm was 2800 rpm. I have another No 2 which I am putting into service in order to do less set up and to have an opportunity to re-pour the main spindle bearings on this one. I intend to run the other at or near 2800 to see how I like it. I suspect it would be better for the tooling. And quieter.

The three step pulley is for feed rates, the rate at which the bed of the machine raises into the cutting chain. The two small leather belts are part of the elevation works. They run in opposite directions and at different speeds. The higher speed is for the table descent.

The paint is a typical dealer fluff and buff paint job. The original color is black.

Chain mortisers cut real fast. The mortising of this door stile for a currently fashionable three point hardware “system” only takes a few minutes.

See the shaft with the spring on it? Follow it down until you just about can’t see it. This is the depth lock. If you are getting one of these machines, do not play with the lower lock while the machine is running until you are real familiar with the pedal control, etc..

This shows the upper range of bar and chain sizes. This one cuts a 3/4 x 2 1/2 inch mortise. These doors are not through mortised so we are only going 3 inches deep here. The bar is long enough to go clear though a 6 inch stile.

The Model 2 is designed for heavy work. It has no problem managing large parts as these stiles cantilevered far off the end of the table. There are two back fence designs in New Britains. Smooth or with the lipped yoke like above and the Model 4 below. A person doing furniture work with curved parts might prefer not to have the lip. But for heavy work like above, the lip is a safer way to go for controlling the part and relieving the clamp some.

Some guys get excited about all the oil. I don’t. It’s gone after sticking and sanding. I use a lot more than I might need to. I would like to put the drip oiler back on but I want a nice brass one. So do too many collectors and hit’n miss-ers, making them real expensive. I’ll use the oil can until oilers fall into my lap.

One thing about old machines, never want something real bad – you will give way too much. Just wait, and good things will happen. That doesn’t mean drag the feet when the hand writing is on the wall in front of your face. The other thing is to avoid the machines everybody wants. Just don’t want them. Then you’ll be free for the real neat things instead.

Years ago I helped someone find an Oliver 125D. It cost more than my entire operation at the time. I have since come into much neater tenoners for a fraction of the cost, which work well and are easy to maintain.

MODEL 1

Here I am well over a hundred years ago. This is a Model 1. The table does not traverse.

This is the linkage showing in the engraving. It appears that when line shaft driven, the tight pulley is engaged for a single pass. May have been a safety feature. I have been reading about rules regarding belts migrating from the loose to tight pulley on their own. This arrangement prohibits that.

This depth rod has a safety collar on it to keep the table from crashing if a guy is not quick.

Here’s the other end with the return spring. I lost the damn loose pulley somehow in the last twenty years. Can’t believe it’s gone but I can’t find it anywhere. I will be removing this stuff soon but I figured I should document it in case I lose it all.

I have this older No 2 running now. The shift linkage I removed and have a motor belted to the tailshaft. The sproket is running at 2700 rpm on this one. This machine is from around 1900. It works really nicely. Now I can take out the spindle on the other one that has served all these years and get it trued up.

MODEL 4

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Speaking of good things happening, this is a recent gift to the shop. Nothing moved on it. I have freed up a few things on it but have much to do. This is a New Britain Model No. 4. It is a foot feed machine designed for lighter work than the No. 2. It is cuter than the No. 2. I will set it up for 1/4″ mortices for screens and cabinet work. I have long wanted one.

This is a cap off the sprocket spindle. It looks real bad. Lot’s of rust and some scoring.

To remove the spindle the blower housing needs to be removed along with the chain tensioner. I am leaving the fan on for now for a reference. The collar on the forward bearing has an indexing hollow in the shaft which is a nice feature for getting the spindle in the right place later. If you are lucky and everything is not rusted stiff, you may be able to work the spindle out towards the front sliding collars and pulley back as you go. But if there is rust and grit in the bearings, be best to lift it out. This shows the Prussian Blue on the cleaned up spindle which came clean with fine emery. There is .002″ run out behind the fan which I believe to be well within my expectations. So I am moving ahead with scraping.

This is quite a contrast from the start. I am about done here. It is often amazing to me how something real bad looking can with a an hour of scraping look pretty good and be ready to run again. The little void was where the pour-er had a chunk of wood to support the shaft. I took it away and will put in it’s place some felt.

This is the gentle persuasion involved in getting the tail shaft out. The idea was to get the collar and pulley to slide off the shaft. Time, oil, and heat help loosen things up.

Then its time to scrape the bearings. This front bearing is wedged between the legs as shown. It was a close fit and required finesse to get it in alignment with the back bearing. So if you don’t need to remove it, don’t. The cap requires a stubby wrench to get the bolts off. Some may question the importance of scraping a 900 rpm bearing. (Some may question the importance of saving this machine.) I just figure I want to do the best I can to get a real nice running machine.

The rear bearing bottom is a difficult, but not impossible scrape. Just need a long scraper is all. And good light.

Here we are starting to go back together. My fan repair failed so I will have to deal with that. Meanwhile, I am getting the shims right and moving ahead getting the rest back together. The blower housing goes on first. The fan onto the shaft from the rear, shaft through the housing through big bearing, collar, pulley, collar, and then through the rear bearing.

Above we can see the tail shaft and pulley put back, bearings shimmed, adjusted. The rear bearing cap adjusted nicely with the four set screws. The front cap is a little tight to get into but creative wrenching does the trick. The pedal is back with its lifting rod, ball jointed disc, and table bracket. What a difference from rusted solid. the action is real nice and smooth.

Every place where two carefully fitted parts come together “2”s are stamped. I have seen this on several machines. My supposition is that this machine is second in a lot built at the same time on the factory floor. Hand fitted parts needed to stay with their mates.

Back together again. Now I need to round up a motor. Scrounge a nice leather belt out of the drums and see how it goes.

Another pretty picture. A few details to fix but it’s pretty done. I am not sure why the chip breaker stop is on the right rather than the left rod. That’s how it was so I figure maybe someone knew something I have yet to learn.

I saw a picture of a machine on the porch of a museum that was on a slab. I though it looked nice and had some additional merits so I decided to try the same. This is some 2′ Douglas Fir splined with our local White Oak. Edges clipped on a jointer.

The belt is some junk belt that will work for a while, maybe longer. I will make an endless belt eventually. The Dutchman is for taking up the slack. I would like to use an old snap switch (Westinghouse) but it requires fuses that thread left. Hmmm. I am sure a little research will help me there. A set collar is in the works to function as the flat belt pulley did to keep the tail shaft from axial drifting. Right now I have a tweak in the belts to keep it from drifting.

The platform gives the extra pedal stroke needed to through mortise sash stiles with wider chain bars (getting deeper than half the radius below the table).

First chips! At first a I spun the sprocket. Tightened that and there we go! Holes! I am wary of putting the walnut chip breaker close until I see the motion of the rods. The clamp is double pitch threaded (?) and requires little hand pressure to secure the work.

More holes. Nice thing about quarter inch bars is they require little power, cut easy and fast. This is going to be great for screens.

The fan blade broke again. I can’t tell what effect that is having. It’s not wildly out of balance like I would have expected. I think I will break off the opposing blade. And see what an exhaust duct does. I don’t think the fan is intended to exhaust this length of bar. When new, these machines were equipped with a “Chip Breaker Chute”. I have four New Britains and once had half of one chute. If they were functional, men would have passed them along it seems to me. But if I find one, I will try it and see if it does anything.

I went through a lot of electrical permutations. I kinda wanted to keep the electrical stuff on the same side of the machine. I am accustomed to have the power on the right on mortisers. Most my starters were real bulky but the old triple pole snap switch was rated right and was solid. So I used it. It had fuse bosses but they were left threaded, unlike any fuse I could find, so I took them out and added overload protection separately. The enclosure for the protection is bolted into the existing hole for the belt shifter lever.

OK but. An electrical expert has pointed out to me that what I have done is ineffective. So don’t do as I do. I will leave this posted tho as a small example of “don’t believe everything you read on the internet.” Lesson over.

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This machine has an interesting story. After spending quite some time outside and almost becoming a mail box holder, these men decided to bring it to me. I tried to resist, having three New Britains already, but it was futile to resist. The two men pictured with the mortiser are big time “enablers”. Men who enable addicts to have yet another heavy old iron machine. In other words, great friends.

TOOLING

The heart of a chain mortiser is the bar, chain, and sprocket. Invented I believe by Mr Renold in England. Chain mortisers predate hollow chisel mortisers but come after power mortisers.

I was salvaging some frozen bars and decided to take one apart to look inside. I have never looked inside. I have old repair kits laying around but I always send my bars to Dick at U S Cutting Chain for repairs. This is a New Britain bar. It is trash, but I thought I would illustrate inside the tip.

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An interesting job of machining. They mean it when the say “Run the Chain Slack”. It is also clear why lubrication is so important.

This view of the bar shows the 3/8″ offset to chain center. Sprockets for these are 3/4″ over all. This, and the numbers stamped on the top of the front of the bar, identify New Britain bars. New Britain bars are not supported for parts, repair or chain. They have unique chain dimensions which are not compatible with brands in use today. This makes New Britain tooling essentially worthless. Too bad, because there is a lot of it out there, well, a lot of bars and sprockets, perhaps not as much unspent chain. (I must say however that I have run some super spent NB chain with barely anything left for teeth and they cut like the dickens!) Maybe someone will make a hobby out of supporting New Britain chain and bar one day.

This is a very small bar tip. It cuts a 1/4×7/8 mortise. I recently opened one of these up and was surprised to find this:

A miniature roller bearing. I had thought them too small for that. This one is spoiled obviously and it is not uncommon to see these burned up. Mini bars take mini chain, .54 pitch, and I personally do not think they are a viable product at 3450-3600 rpm.

We aren’t exactly a large market for chain mortisers. Although I personally believe everyone should have one. Throw out the biscuits, dowels, slot mortisers, hollow squealy things and bring on the chains. Let’s build a mortice and tenoned America. No more cheap stuff. No more re-invent the wheel.

Generally, supportable bars have an 1/2″ offset to chain center and 1″ sprockets. Brands are U S Cutting Chain, Renold, Monk Worlsey Monk, and Field. The first three are compatible with each other. Field equipment needs it’s own sprockets and it has some non-standard chain pitches. They are 3/4 high like NB and occasionally one will find a combo sprocket.

Sprockets are 5/8″ ID. 1/2″ are in my collection for New Britain bars.

This is Field equipment. Some bars can be re-tipped. Needs it’s own brand of sprockets, the size of which is shown on the bar. This is an example of a nearly new chain with a softwood grind.

U S CUTTING CHAIN

As of 2011, U S Cutting Chain has closed it’s doors. I am forever indebted to Dick LeDuc for his generous and kindly advise, support, and service. I wish him a long and rewarding retirement.

The name U S Cutting Chain has been adopted by an importer (Timber Tools) of chain operating out of New York and Ontario, http://uscuttingchain.COM. But I cannot vouch for them at this time.

Woodworkers Tool Works has expressed a willingness to fill the void by importing Keil brand from Germany and in providing repairs and custom work. Unfortunately, the Keil chain pitches may differ from Renold, M W and US Cutting chain.

Leitz carries a line of chain, bar, and sprockets with the fullest range of offerings on paper at least.

www.gerrymet.co.uk/acatalog/Imperial.html

This British company stocks basic sizes in .89 pitch and Imperial/American sizes. They make special orders, are highly experienced, and have excellent customer service.

http://www.snookssaw.com/

This shop does a real nice job sharpening chains.

Most of us in the chain mortiser community will eventually need to go metric. Matching our hollow chisel machines to the chains will require changing their tooling as well and get rid of the Forest City and Greenlee stuff. I suppose FC could go metric, but I doubt it. Many guys say the imported hollow chisels work better anyhow.

TRUING UP A WORN BAR MOUNT

The little mortiser was making crooked cuts in the smallest bars. Turns out the mount was wore from the narrow bearing of the small bars. The bar was not seating true. I shimmed around but could not get it right, so I took it to the machine shop. I was reluctant because that can be costly. But so are bad mortises.

Turns out it was an easy and fast fix. And what I took off here I compensated for by adjusting the sprocket. A nice feature of the New Britains are the removable sprocket arbors.

Another video after a tune up:

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