Converting Stihl 015L Chainsaw from 1/4″ to 3/8″ Pitch

I received a non-working Stihl 015L Chainsaw the other day to repair. I disassembled and took apart the carburetor where years of neglect and ethanol fuel had taken its toll. After cleaning everything out and a new set of gaskets I got it started and went to town on a dead tree in my backyard. After I quickly realized the tree was starting to smoke and I wasn’t making much progress through the branches. After examining the chain I came to conclusion that… the chain was as dull as a butter knife. I also noticed that the chain would rotate around the bar even when the motor was idling. The service manual said to adjust the idle throttle if this was happening, but even when the motor was about to die it was idling so slow the chain was still turning.

Being quite the novice at sharpening chainsaws I decided to get a new chain instead. Looking online I found a few forums talking about upgrading the 015L from 1/4″ to 3/8″ pitch.

First I would need a new sprocket and needle bearing to match.
I would also need a new chain and bar to run the new setup. I read that a 1/4″ pitch bar wouldn’t work well with a 3/8″ pitch chain even though they were both .050G due to the shape of the nose.

Unfortunately since the saw hasn’t been produced since the 80’s some of the parts were hard to come by. Mainly the oil pump gear that connects the clutch to oil pump, which I couldn’t find anywhere. My local Stihl dealer told me the part wasn’t available for purchase. I found a seller on eBay that manufactures their own replica part, for over $40 a piece. “There has to be a cheaper way for penny pinching Matt!” I thought to myself. After a few minutes of googling I came across this, a STL to 3D print a copy of the gear from the comfort of my own home! Since the gear doesn’t receive and real stress when the oil pump is operating correctly printing this piece out of ABS with 60% infill would be able to withstand the forces applied from the clutch.

The difference from the old and new part was the pattern the clutch uses to drive the oil pump. The sprocket that moves the chain is also used to power the oil pump gear, so if the pitch of the chain changes the positioning of the sprocket had to change as well.

1/4″ vs 3/8″ pitch design

Hot off the print bed! It took me 3 tries with different speeds to find an acceptable quality part. I ended up printing around 20 mm/s, 60% infill, 0.1mm layers, and 0.6mm sidewalls with a .6mm extruder nozzle.

I did have to ream the inside out a little bit to get it to fit on the shaft. I tried to mimic the amount of friction the existing part had.

An image of how the new part interacts with the oil pump gear.

Once the cover was back on things were looking good!

The sprocket and needle bearing were then installed. Fit the printed part like a glove.

side by side the differences between the sprockets becomes more visible

I noticed when I installed the new sprocket that the old one had significant amount of clutch foot material on the outside of it. The clutch is designed to disengage the chain when the engine speed is slow so the saw can be handled easier. Once throttle is applied to the motor the clutch engages and the chain starts to turn. Since there is friction between the clutch and the sprocket the foot has padding on it to prevent metal on metal contact. Since there was a bunch of material built up I thought that might be why the chain was turning while the motor was idling. After installing everything later on I realized my printed part was not deep enough for the sprocket, which was making the sprocket push against the clutch washer, negating the clutch completely and making the chain move while idling. I removed the part and filed out some of the material where the sprocket meets the gear to make it sit flush. After I finished that I could freely spin the flywheel without engaging the chain.

The new chain on top, old on bottom.

Bar size comparison:

Notice the new bar is a bit taller at the end.

Sprocket size difference at the end of the bar to fit the 3/8″ size chain.

The new chain installed around the new sprocket.

I also rewound the starter pulley and spring. Before the handle and rope would hang over the side of the chainsaw when running which was mighty annoying and pretty stupid looking.

I will be checking periodically to see how well the ABS printed part is holding up. I’ve been looking into printing with nylon filament. If the ABS part is not able to withstand the forces put upon it I will recreate it using nylon instead.

Nelly’s Security Complete 8 Channel 1080P HD-TVI Dome Surveillance System Review

Nelly’s Security contacted me to write a review of their new 8 Channel HD-TVI system complete with video examples of a real-world installation in several different settings. In exchange for this review I was allowed to keep the unit as a gift.

The NVR is a NSDV-208QK, which is a rebranded Hikvision DS-7208HQHI-K1. OEM versions of Hikvision NVRs look pretty different from their retail counterparts, but inside the guts are the same. Nelly’s supplies the NVR with a 1TB Seagate Surveillance hard drive for recording the camera action. The NVR main board has space for 1 SATA drive, adding additional storage in the future will require removing the 1TB and replacing it with a new one. Unfortunately this case doesn’t have the ability to be mounted inside of a rack, but a simple shelf holds the NVR and provided power supply with ease.

Under the hood

Powering the cameras comes from an external power pack, similar to a laptop charger. A splitter then takes that power source and allows 8 cameras to be plugged into it. The NVR has its own power source separate from the cameras.

The cameras are NST-1080P-DM1, a model carried by Nelly’s. It has a 1/2.7″ OV 2.1MP CMOS sensor. It is IP66 rated which means it will work fine as a outdoor camera. The 3.6mm lens offers a wide field-of-view. Not many other details were available on Nelly’s site about this camera model.

The camera is comprised of several parts following a similar design to other turret style cameras.

and the pigtail is a typical 12v and HD-TVI connection.

In true Matt LaPaglia fashion I tore it apart (this will most likely void your warranty)

No clues on the inside as to who manufactures the lens. It did reveal the weatherproofing done to the pigtail to keep the elements out, the desiccant pack, and a nice rubber gasket where the two halves of the camera shells meet

There are several ways to install HD-TVI cameras. I opted for using ethernet and Balun adapters to connect the ethernet wiring to the cameras. The system I received included a 1000′ spool of ethernet to do this. For this installation I will be using ethernet already run to the camera mounting points for my existing system. The spool I received was good quality with solid copper conductors.

The Balun connector is used to transmit video (green and white/green), the rest of the wires are used for power (solid colors for positive, striped for negative)

Each camera is connected using the balun adapters. One of the four pairs of wires in each ethernet run is used for the video signal. The other 3 pairs are used to send power from where the NVR is to the camera. One reason I liked this approach over siamese cabling the the potential for upgrades down the road. If one decided to stick with HD-TVI they would be fine either way, but if someone wanted to upgrade to IP cameras later having the ethernet already run would be substantially easier. Just chop the ends of the wires off and terminate them with a network jack.

Since these are non-IP based cameras they don’t have a way to automatically control the gain or shutter speed used. This means these cameras won’t perform well for license plate capture at my mailbox because the camera will be pumping up the gain automatically at night which will overexpose the license plates and create white blurs. For general surveillance purposes this isn’t an issue however. The camera’s automatic exposure settings perform well during the day and night.

A quick day time indoor demo:

The on-board IR is decent for close quarters. When subjects are within 15-20 feet of the camera details come into focus for good facial recognition. Cameras placed next to doors or entryways got acceptable images of the occupants. I did not notice any bleeding of the IR into the lens due to the physical separation of the lens and IR LEDs. I noticed that if I manually turn the IR on by putting my finger over the sensor, and then slowly pull my finger away from the sensor, I could get the LEDs to “dim” slowly away until they finally turned off and the IR cut filter clicked back into place. I didn’t notice this affecting actual surveillance because this issue would only occur right before it would be bright enough to switch to day mode anyway. When transitioning from night to day mode the sensor seems much faster at getting correct exposure than some of my Hikvision cameras. On my IP cameras it takes the sensor 2-3 seconds to adjust the camera exposure to get an acceptable image.

Here’s a quick demo of the camera positioned inside a front door:

And outside facing the backyard:

The cameras are very easy to position once attached to a structure. Instead of having a set screw to hold the camera in place the base has a ring that turns to tighten the camera to the mount. The cameras are fairly discrete. I don’t have any size comparisons other than Hikvision models, but they are smaller than the 3mp EXIR turret with about half the footprint. The HD-TVI and power connector are much smaller than an ethernet pigtail, allowing me to drill smaller holes in my house to run the pigtail through into the attic.

Attaching the cameras to the NVR is trivial. After plugging a camera in the NVR was detecting and recording from it within 5 seconds. No worrying about passwords or individual camera settings that come with IP cameras.

Nelly’s currently sells this system for $399 through their website. This system is at an excellent price point considering it includes a NVR with 1TB of storage, 8 cameras, and a 1000′ spool of cat5 for wiring. The NVR comes with a 3 year warranty and the cameras a 1 year warranty. For the beginner looking to get into CCTV this would be a fool-proof system to start with.

To Infinity, Recursively!