Danarm 55

[heimannm]

My apologies to Captain Dangers for the long delay in getting to this saw. I received this one perhaps in January or February but kept getting occupied with other projects.

I was intrigued by the photos of the LH and RH versions the captain put up and he was willing to help get one to me. Mike Acres site says "COMMENTS: Saw is virtually identical to McCulloch 1-10 " so I thought I'd see for myself. This one happens to be a RH start version.









The saw would not turn over as received. I like to take them all the way down for a good cleaning in any case so let's have a look under the covers.



Carburetor is a Tillotson HS, the air filter appears to be very close to the hard version found on early -10 models.



Under the flywheel, a few obvious differences are the location of the condenser (attached to the coil) and the points box itself.





Inside the points box, the components are different from the 10 Series indeed. One similarity is certain rubber parts just turn to goo like the grommet over the primary wire from the points.



Mark

 

[heimannm]

The Danarm has a heat shield between the engine block and the air box/fuel tank that McCulloch 10 Series saws do not have.





While similar to the McCulloch 1-10 there are many difference. The 55 does not have the screw between the oil tank and the fuel tank, other fasteners are different including the way the air box is secured to the block, and the fasteners holding the block together...1/4-28 on the Danarm where the Mac uses 12-24. As you can see below, we are beginning to understand the difficulty rotating...



The seals are also different, larger O.D. on the PTO side and wider on the flywheel side. The retaining ring for the flywheel side bearing is also different, a genuine Tru-Arc style snap ring that holds the bearing in place. The cylinder looks to be O.K. and the piston looks good as well. I will have to take the flywheel side ball bearing off and find a suitable replacement, PTO side is the same BH108 as any 10 Series Mac. Hopefully the crankshaft and connecting rod are O.K. under the oxide dusting. I think most of that is actually from the magnesium oil tank half of the crankcase.

I didn't record it in any of the photos but the Danarm utilizes the three screw mount for the automatic oil pump. Based on the looks of the automatic pump when I took it out, I may get to find out if the McCulloch parts will in fact bolt in.

Finally, the piston had locating pins for the ring ends, a feature McCulloch did not include until the 7-10 and later editions of the PM55 models. I will have to see if I can find or modify some rings to work in this saw.



More to come as I get this one cleaned up for a better inspection next week.

Mark

 

[RolandM]

Mark,

If you need spares, I have two or three 55 parts saws lying around in various buckets. The MkIII model is quite different to the earlier ones.

Roland.

 

[heimannm]

Thanks Roland - I will keep that in mind if I run into a problem. I did some cleaning on Saturday morning and it looks like the crankshaft and connection rod will be O.K. The flywheel side bearing is stuck so I will remove it and get some good measurements, appears to be a standard bearing like 6202 perhaps.





The transfers are definitely different from a standard 10 Series McCulloch with a curved shaped to direct the charge to the intake side of the cylinder, evidently to achieve a more efficient discharge of the exhaust.

Danarm 55



Mac 10 Series



The biggest difference so far, the Danarm has a removeable head.





More cleaning will be required on the remaining parts and then we will see just what may be needed. I would like to replace the rings while I'm in there but the ends are peculiar to accommodate the locating pins...I'll try to put up some photos when I can.

Mark

 

[RolandM]

Mark,

Looking good. I dont have an early 1 10 series Mac, only familiar with later 10-10 so its interesting to see McCulloch had chrome cylinder from the start.
My take on the detachable cylinder head, which was a feature on the Danarm 1-71-ss too is its a reflection of British foundry skills at the time. As far as I know we ( in Britain ) never have mass produced closed cylinder plated cylinders over here for any small engine application.
However, what you have in the 55 is a "cast in" iron cylinder complete with the transfer port feature. The open cylinder making machining and honing possible on conventional machinery. One thing about that cylinder is its weight, its a fair old lump. The technique used to bond iron to the aluminium outer shell is often known as the Al-fin process and many post war British motorcycles carry this lettering on their cylinders. It was also used to produce car brake drums with iron friction surface, and an exotic looking aluminium cooling surface.
As I have mentioned before, the MK III 55 has a one piece closed chrome cylinder - imported from Galidoni, which is much lighter and probably much cheaper to produce.

Roland

 

[heimannm]

Interesting history Roland.

Many of the early 10 Series saws including the Mac 10-10, Mac 10-10A, Super 10-10, and Pro 10-10 saws had a cast iron sleeve. I think the later 7-10's were the first models to have a chrome plated aluminum bore. Any 10 Series CP, SP, or PM (Pro Mac) model had the chrome plated aluminum bore.

For the large frame saws, basically everything was sleeved except the SP/PM105, SP125C and 895C.

Most Mini Mac and all Power Mac 6 were chrome plated aluminum cylinders. There were a few odd Mini Mac models with plain aluminum bore and chrome plated pistons.

Mark

 

[RolandM]

Mark,

The Al-fin process used a cast iron cylinder which was left rough as cast on the outside. It was then placed in the mould for the second process which was to pour the aluminium outer shell. The rough cast iron provided a mechanical grip to the outer aluminium shell, but there was I believe a more intimate bond at a molecular level too. I think the process was a war-time development for piston aero engines, and was very fashionable with performance British motor cycles in the 1950's.

This is quite distinct from the more familiar pressed in or shrink fit iron sleeve, with machined surfaces all over and typically fitted with several thou of interference fit.
I am confident that the iron cylinder McCullochs I have stripped and the Danarm 1-71-ss use simple iron interference fit sleeves.

I would be interested on your thoughts on the piston / rod and crank. The cranks will not interchange as the Danarm Wipac points have the opening cam placement at a different angle. It to me sees very probable that the forgings were done in the same place.They look so similar. Danarm also used the McCulloch style outboard needle bearings for piston etc. Clutch and drive drum interchange.

Roland

 

[heimannm]

I have made a small amount of progress, I did manage to get the bottom end of the crank case cleaned up, got started on the automatic oil pump, and did some further investigation on the crank/rod bearings. Not good...



The crankshaft and connecting rod will clean up all right for no more that this one will run. I will use some rod bearings from another 10 Series project to put this one together.



I did pull the flywheel side crankshaft bearing that was stuck and would not rotate. I found a suitable replacement in my bearing file, not a new bearing but certainly good enough for this project. My goal is to make it run, make a cut with it, then put it on a shelf to display in the museum when it get built later on this year.

Mark

 

[Conquistador3]

The Alfin (also known as Ni-resist or Al-fin) process was originally created for piston ring groove inserts by the Wellworthy Piston Ring Company. They were very used in pre-WWII diesel engines to reduce ring groove wear, a serious problem in diesel engines due to their compression. The DuraBowl process now used by Federal Mogul and other diesel piston manufacturers is nothing more than a fancier, computer controlled version of the old Alfin process. Ni-Resist refers to the steel alloy used for the lining in later iterations of the process, as it's far more durable than simple cast iron.
In 1947 they merged with the British Piston Ring Company and Hepson & Grandage to form the Associated Engineering Group: Alfin was further developed in that timeframe to manufacture other engine components and I think the first Alfin cylinder blocks were delivered to BSA in 1950.
I think there are still many diesel engines around using Alfin ring inserts out there: Japanese manufacturers loved the process, albeit it never migrated to cylinder casting there.

 

[Little Al]

The Alfin (also known as Ni-resist or Al-fin) process was originally created for piston ring groove inserts by the Wellworthy Piston Ring Company. They were very used in pre-WWII diesel engines to reduce ring groove wear, a serious problem in diesel engines due to their compression. The DuraBowl process now used by Federal Mogul and other diesel piston manufacturers is nothing more than a fancier, computer controlled version of the old Alfin process. Ni-Resist refers to the steel alloy used for the lining in later iterations of the process, as it's far more durable than simple cast iron.
In 1947 they merged with the British Piston Ring Company and Hepson & Grandage to form the Associated Engineering Group: Alfin was further developed in that timeframe to manufacture other engine components and I think the first Alfin cylinder blocks were delivered to BSA in 1950.
I think there are still many diesel engines around using Alfin ring inserts out there: Japanese manufacturers loved the process, albeit it never migrated to cylinder casting there.

I had a 350 single cylinder AJS trials bike 1948 but 49 model with an Alfin cylinder & alloy head no idea if they or the "Beezers" came first they also did Alfin Brake drums on early post war sports cars lovely looking finned "jobbies"

 

[Modifiedmark]

Interesting thread Mark. I was also curious about these. I actually tried to buy one myself a while back but typical of Craigslist flakes I never got a reply from the seller.

 

[captain dangers]

doing a grand job mark ;o)

 

[heimannm]

Weather was lousy outside today so I was able to spend some time putting the 55 back together. After my last session I found a set of rod bearings for the 10 Series and put the rod/crankshaft together.



Another difference from the McCulloch version, the rod bolts are threaded into the cap rather than into the rod itself.



Since the rings were somewhat unique and still had a lot of spring to them, I went ahead and put them in after cleaning up the cylinder.



I was doing a bit of final clean up on the cylinder and really noticed how the entire cylinder with ports is one casting with the aluminum cast over it. If you look closely you can see how the original mold had a flaw with this cylinder was cast with some iron in the transfers. Don't worry about that coming loose, it is part of the casting.



Going back together now.



The ball that plugs the cross drill in the oil passage was missing so I found one in a small parts assortment and knocked it in.



I always like to make sure the oiler is working before assembling one of these type saws. Even more important on one like this with the three screws securing the automatic oil pump in place. You can see a little dribble down the side...after I replaced the ball...after it squirted me in the eye (glasses).



This saw had some severe corrosion, the lower mount for the front handle is almost completely gone. The muffler is very much like the McCulloch version.



I had to spend quite a bit of time sorting out some ignition issues. First was no continuity through the points, clean, clean, then clean them again and the points were working. Condenser was fine. There was an issue with the coil/plug wire, ultimately I determined the plug wire was open on both ends. I was able to reseat the wire on the coil end and replace contact and boot on the plug end.



I got this far when I had to come in for the day and get cleaned up for supper.



Mark

 

[heimannm]

Worked on the Danarm55 Mark II a bit more today. Carburetor is a Tillotson HS with the high speed governor. Very clean, simple design and lots of room to work "under the hood".





The Damarm folks came up with a good alternative for the McCulloch style fuel line with the molded in grommet. Instead, they use a type of multi-piece combination grommet and barb fittings along with some straight fuel lines. I only had to replace the fuel filter, everything else was good to use again. I did have to replace the cork gasket in the fuel tank, good thing I received a package from Sawzilla last week with some of their Viton 10 Series fuel tank gaskets.





I ended up replacing the flywheel side bearing, both seals, the fuel filter, the spark plug boot and connector, exhaust gasket, automatic oil pump gasket, and the connecting rod bearings as well as the fuel tank gasket.





Mark

 

[heimannm]

Here it is all together. Fired right up, revs nicely, manual and automatic oil pumps work (I spent a couple of hours cleaning and working on the automatic oil pump to make sure it would be O.K.), I even cut up the remains of last year's Christmas tree just to make sure. It does seem to weep a bit of fuel from the fuel cap, also seemed to be leaking from one of the tapped holes for the screws that hold the flywheel cover in place when the screw was out. I have never seen that on a McCulloch saw but it was fine with all of the screws in place.

You can see in the background that I had to put up some shelving in the current shop to hold some of my "display saws" while the museum is being built. I have really run out of space in my current shop but have not stopped collecting so every surface is covered.









They even went all out with the vent in the fuel cap, nice system with a rubber seal, aluminum back up, and a spring under the three screw cover.





I'll take it to the GTG in Bendavis, MO this weekend and cut a little, then clean it up when I get back in preparation to go on display once the museum is ready.

Mark

 

[RolandM]

Mark,

Nice write up! I always have my Frontier branded Danarm 55 to hand. A handy tool, light, compact and easy to use. I keep a 16" bar on mine which suits it well, but it will happily chug away on a 20.
Roland.

 

[old 040]

Nice build Mark, I always wondered just how much the Danarm 55 and McCulloch 1-10 were the same, this AV version is quite unique with what looks to be a very cheesy looking spring set up.

 

[captain dangers]

Here it is all together. Fired right up, revs nicely, manual and automatic oil pumps work (I spent a couple of hours cleaning and working on the automatic oil pump to make sure it would be O.K.), I even cut up the remains of last year's Christmas tree just to make sure. It does seem to weep a bit of fuel from the fuel cap, also seemed to be leaking from one of the tapped holes for the screws that hold the flywheel cover in place when the screw was out. I have never seen that on a McCulloch saw but it was fine with all of the screws in place.

You can see in the background that I had to put up some shelving in the current shop to hold some of my "display saws" while the museum is being built. I have really run out of space in my current shop but have not stopped collecting so every surface is covered.

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They even went all out with the vent in the fuel cap, nice system with a rubber seal, aluminum back up, and a spring under the three screw cover.

View attachment 688041

View attachment 688042

I'll take it to the GTG in Bendavis, MO this weekend and cut a little, then clean it up when I get back in preparation to go on display once the museum is ready.

Mark

how did it perform mark at the gtg? CD

 

[heimannm]

My temporary repair of the spark plug lead proved to be too temporary...

Mark

 

[captain dangers]

My temporary repair of the spark plug lead proved to be too temporary...

Mark

oh I see ;o) will she be going out again when sorted ? I have just got frontier 5r up and running , which is a danarm 55 mk3 in orange livery , single component Gilardoni cylinder so doesn't have the removable cylinder head. I have managed to get my blue/silver mk2 left hand 55 I rebuilt running in a fashion, i think the condenser or coil has had it, it runs for 5-10 secs then shuts down and will start again after 1-2 mins . nice job on the museum too Mark I only wish I was closer, be nice to have paid a visit. CD