RCinNC
Well-Known Member
Back in 2017 I rebuilt a Slime tire inflator into a unit that would fit into my tool tube, because I wanted to always have one on the bike and not take up any room in the panniers. The thread is here at https://yamahasupertenere.com/index.php?threads/project-putting-your-air-compressor-on-a-diet.22975/ , but the photos have all disappeared, so it’s not of much value any more.
The inflator worked out well, but over the years of use I did identify some areas that I wanted to improve on. These were the main issues:
To make my original homemade unit smaller, I put the power switch in the power cable itself rather than in the inflater. That made the power cable too bulky to store it in the tool tube with all the other stuff in there, so I had to keep it in one of my crash bar bags. That made it more of a pain to use it. So, I wanted to incorporate the power switch into the unit itself this time, even though it would make it a little larger. The switch would have to be recessed to protect it from impact.
I wanted the air hose to be detachable from the inflator, so the inflator would fit in the tool tube. The original air hose I made for my first inflator didn’t have a swiveling fitting where the hose attached to the inflator. That made it difficult to attach the hose, since you had to swivel the entire hose in order to screw it onto the inflator. I wanted it to have a fitting that didn’t require spinning the hose.
My original homemade inflator had an ABS plastic housing. It worked, but I wanted something more durable that could stand up to impact it if someone dropped it, or accidentally stepped on it. That meant an aluminum housing.
I bought a Slime tire inflator from eBay so I could use the motor and pump. The unit’s now out of production. It was the same kind that I used in the original inflator; I liked it because the motor and pump were really robust, and a better quality than a newer inflator I’d bought and took apart.
I believe one reason these compact tire inflators fail is inadequate wiring, mainly in the switch. All the ones I’ve seen have used AC rated switches in a 12 volt DC rated circuit. For occasional use, it’s no problem, but 12 volt circuits can be hard on AC rated switches, and I suspect that a lot of complaints that these pumps “burned up” was the switch failing. I wanted to use a DC rated switch, and I also wanted to use heavier gauge wiring than the original pumps used.
The project started with a plan, drawn up on Inkscape. This is a screen capture of a portion of that plan.
Those plans are then used to create templates. I print them on standard copy paper, then double the thickness of the paper to make the template more durable (I spray glue another sheet of copy paper to the paper with the template). The templates are then cut out and spray glued to the various plastic and aluminum parts to be used as cutting and drilling guides.
This is what one of those templates look like. It’s glued to the part that became the base of the unit.
This is a photo of the chassis of the inflator. I wanted to build everything into the base of the inflator, so the cover could be easily be removed if necessary (for example, I didn’t want to have the switch mounted in the cover).
I tried to use as much of my scrap pieces of aluminum as I could. The end bulkheads were made from 5/32” aluminum plate and 1/8” aluminum angle, because I didn’t have any pieces of 1/8” angle with long enough legs. I had the 5/32” plate left over from a pannier attachment project.
Here’s the chassis, with most of the components except the motor/pump installed. I incorporated a small 12 volt cooling fan from a computer printer into the inflator to help keep it cool. The fan is always running when the motor is running. The fan is at the lower right part of the chassis. The switch is an illuminated rocker switch, rated for 12 volts DC and 16 amps.
This is the cover under construction. It’s made from pieces of 1.5 mm aluminum sheet. I don’t have a bending brake, so I joined the pieces using 1/16” aluminum angle and stainless steel hardware. Holes were drilled in the top and sides to provide ventilation to dissipate heat.
This is the air hose fitting I made. It’s a 1/8” NPT female fitting with a 3/16” hose barb and a tank valve. One side of the tank vale is a Schrader fitting (basically the same type of valve in your tire). The tank valve was threaded into the 1/8” NPT fitting, with a small brass plate sandwiched between them, and then it was all soldered together. The hex part of the fitting fits through a hex hole in the bulkhead that I made with a drill and a file, and the brass plate bolts to the bulkhead.
This is the completed unit, without the cover.
Here’s the finished unit. It’s powered up in this photo, and you can see the illuminated and recessed 12 volt switch. It lights up whenever there’s power to the unit. I also added the reflective tape to the top of the unit to make it easier to find if I drop it somewhere in the dark. You can see the cooling fan through the vent. The inflator was painted with low gloss high temperature engine enamel, because I had a can of it on the shelf.
This is the exterior of the air fitting where it passes through the bulkhead. I removed the valve core from the fitting to make sure there’d be unrestricted air flow through the fitting.
Here’s the air hose attached to the Schrader valve on the inflator: I found an extension hose for a Viair compressor that had the exact fitting I needed to thread onto the Schrader valve. I cut off the end of the hose with the male fitting and attached a chuck with a homemade wire hose clamp. This fitting lets me screw on the air hose without having to twist the entire hose.
This is the power cable attached to the unit. The cable is a 14 gauge extension cable with two pin connectors at each end; it’s sold as an extension cable for a solar panel. The connection point within the inflator is another two pin connector, boxed in with ABS sheet plastic and screwed into the chassis. The inflator plugs into a fused two pin power cable wired directly to the battery on the bike.
This is the power cable. I added an extension that ends in a cigarette lighter outlet style plug. I set it up that way just in case someone needed to borrow the inflator but didnt have a two pin connector on their bike.
To keep everything compact and organized inside the tool tube, I made a cable reel out of ABS sheet plastic and a section of PVC pipe and coiled the power cable up on this reel.
Here’s the unit and the cable reel, stacked up and inserted in the tool tube. I added some feet to the unit to cut down on the tendency of these small inflators to dance around when they’re on a hard surface.
For reference, this is a size comparison between the original housing for the motor and pump and the custom made unit.
I tested the unit out once it was finished. I aired my front tire down to 10 pounds PSI and then refilled it. It took two minutes forty seconds to get the tire up to 37 pounds PSI. The housing on the inflater was only very slightly warm to the touch. One advantage to the removable cover is that, if necessary, I could remove the cover for better ventilation without affecting the function of the inflator.
The inflator, power cable and air hose all fit into my tool tube, along with my tool roll. Even if I remove the panniers and crash bar bags, I’ll always have a way to repair a flat on the bike.
All the parts for this were made with fairly basic tools: hacksaw, drill, files, small tap and die set, etc. I do have a small benchtop drill press which definitely increases the accuracy of the project.
The inflator worked out well, but over the years of use I did identify some areas that I wanted to improve on. These were the main issues:
To make my original homemade unit smaller, I put the power switch in the power cable itself rather than in the inflater. That made the power cable too bulky to store it in the tool tube with all the other stuff in there, so I had to keep it in one of my crash bar bags. That made it more of a pain to use it. So, I wanted to incorporate the power switch into the unit itself this time, even though it would make it a little larger. The switch would have to be recessed to protect it from impact.
I wanted the air hose to be detachable from the inflator, so the inflator would fit in the tool tube. The original air hose I made for my first inflator didn’t have a swiveling fitting where the hose attached to the inflator. That made it difficult to attach the hose, since you had to swivel the entire hose in order to screw it onto the inflator. I wanted it to have a fitting that didn’t require spinning the hose.
My original homemade inflator had an ABS plastic housing. It worked, but I wanted something more durable that could stand up to impact it if someone dropped it, or accidentally stepped on it. That meant an aluminum housing.
I bought a Slime tire inflator from eBay so I could use the motor and pump. The unit’s now out of production. It was the same kind that I used in the original inflator; I liked it because the motor and pump were really robust, and a better quality than a newer inflator I’d bought and took apart.
I believe one reason these compact tire inflators fail is inadequate wiring, mainly in the switch. All the ones I’ve seen have used AC rated switches in a 12 volt DC rated circuit. For occasional use, it’s no problem, but 12 volt circuits can be hard on AC rated switches, and I suspect that a lot of complaints that these pumps “burned up” was the switch failing. I wanted to use a DC rated switch, and I also wanted to use heavier gauge wiring than the original pumps used.
The project started with a plan, drawn up on Inkscape. This is a screen capture of a portion of that plan.
Those plans are then used to create templates. I print them on standard copy paper, then double the thickness of the paper to make the template more durable (I spray glue another sheet of copy paper to the paper with the template). The templates are then cut out and spray glued to the various plastic and aluminum parts to be used as cutting and drilling guides.
This is what one of those templates look like. It’s glued to the part that became the base of the unit.
This is a photo of the chassis of the inflator. I wanted to build everything into the base of the inflator, so the cover could be easily be removed if necessary (for example, I didn’t want to have the switch mounted in the cover).
I tried to use as much of my scrap pieces of aluminum as I could. The end bulkheads were made from 5/32” aluminum plate and 1/8” aluminum angle, because I didn’t have any pieces of 1/8” angle with long enough legs. I had the 5/32” plate left over from a pannier attachment project.
Here’s the chassis, with most of the components except the motor/pump installed. I incorporated a small 12 volt cooling fan from a computer printer into the inflator to help keep it cool. The fan is always running when the motor is running. The fan is at the lower right part of the chassis. The switch is an illuminated rocker switch, rated for 12 volts DC and 16 amps.
This is the cover under construction. It’s made from pieces of 1.5 mm aluminum sheet. I don’t have a bending brake, so I joined the pieces using 1/16” aluminum angle and stainless steel hardware. Holes were drilled in the top and sides to provide ventilation to dissipate heat.
This is the air hose fitting I made. It’s a 1/8” NPT female fitting with a 3/16” hose barb and a tank valve. One side of the tank vale is a Schrader fitting (basically the same type of valve in your tire). The tank valve was threaded into the 1/8” NPT fitting, with a small brass plate sandwiched between them, and then it was all soldered together. The hex part of the fitting fits through a hex hole in the bulkhead that I made with a drill and a file, and the brass plate bolts to the bulkhead.
This is the completed unit, without the cover.
Here’s the finished unit. It’s powered up in this photo, and you can see the illuminated and recessed 12 volt switch. It lights up whenever there’s power to the unit. I also added the reflective tape to the top of the unit to make it easier to find if I drop it somewhere in the dark. You can see the cooling fan through the vent. The inflator was painted with low gloss high temperature engine enamel, because I had a can of it on the shelf.
This is the exterior of the air fitting where it passes through the bulkhead. I removed the valve core from the fitting to make sure there’d be unrestricted air flow through the fitting.
Here’s the air hose attached to the Schrader valve on the inflator: I found an extension hose for a Viair compressor that had the exact fitting I needed to thread onto the Schrader valve. I cut off the end of the hose with the male fitting and attached a chuck with a homemade wire hose clamp. This fitting lets me screw on the air hose without having to twist the entire hose.
This is the power cable attached to the unit. The cable is a 14 gauge extension cable with two pin connectors at each end; it’s sold as an extension cable for a solar panel. The connection point within the inflator is another two pin connector, boxed in with ABS sheet plastic and screwed into the chassis. The inflator plugs into a fused two pin power cable wired directly to the battery on the bike.
This is the power cable. I added an extension that ends in a cigarette lighter outlet style plug. I set it up that way just in case someone needed to borrow the inflator but didnt have a two pin connector on their bike.
To keep everything compact and organized inside the tool tube, I made a cable reel out of ABS sheet plastic and a section of PVC pipe and coiled the power cable up on this reel.
Here’s the unit and the cable reel, stacked up and inserted in the tool tube. I added some feet to the unit to cut down on the tendency of these small inflators to dance around when they’re on a hard surface.
For reference, this is a size comparison between the original housing for the motor and pump and the custom made unit.
I tested the unit out once it was finished. I aired my front tire down to 10 pounds PSI and then refilled it. It took two minutes forty seconds to get the tire up to 37 pounds PSI. The housing on the inflater was only very slightly warm to the touch. One advantage to the removable cover is that, if necessary, I could remove the cover for better ventilation without affecting the function of the inflator.
The inflator, power cable and air hose all fit into my tool tube, along with my tool roll. Even if I remove the panniers and crash bar bags, I’ll always have a way to repair a flat on the bike.
All the parts for this were made with fairly basic tools: hacksaw, drill, files, small tap and die set, etc. I do have a small benchtop drill press which definitely increases the accuracy of the project.
