Shop Mods of early 2018
In February 2018 I decided that
several things needed to happen in my shop: The first
3 of these in addition to a major cleanup were to refinish my primary
workbench, to add heating and cooling to my shop, and to make a stock
rack.
Bench refinishing
Fifty four years ago I built a workbench. Its structure included a top of wide 2 inch lumber. I scrounged at a local lumberyard and found some remnants of narrow oak flooring and used that to provide the working surface of my bench. It has served me well for all those years, but it is suffering from a combination of a prolonged heavy workload and the dry Arizona climate which has shrunk the boards creating gaps. It is time to correct these conditions
As you can see, the urethane finish has gotten beat up and the gaps between boards that have
developed are actually capturing small parts.
Bench refinishing
Fifty four years ago I built a workbench. Its structure included a top of wide 2 inch lumber. I scrounged at a local lumberyard and found some remnants of narrow oak flooring and used that to provide the working surface of my bench. It has served me well for all those years, but it is suffering from a combination of a prolonged heavy workload and the dry Arizona climate which has shrunk the boards creating gaps. It is time to correct these conditions
As you can see, the urethane finish has gotten beat up and the gaps between boards that have
developed are actually capturing small parts.
I thought about using a stripper
and
starting with bare wood, but decided that sanding, filling the gaps,
and final sanding were the best approach. After a LOT of sanding,
filling seemingly miles of cracks, and even more sanding, I was ready
to apply the new finish. Three coats of a water based "oil
enhanced" urethane later and my bench was smooth topped and beautiful
again!
Here you can see the major improvement.
Here you can see the major improvement.
Heating and
Cooling
During the summer and winter, my shop can get uncomfortably hot or cold. When I was refinishing my workbench, the shop temperature was 45 degrees. It took a couple hours of running two electric heaters to get above the minimum refinishing temperature of 55. I have been planning all along to add temperature control, but until now, I just haven't!
I want a window size unit which has a heat pump as well as air conditioning, and which can be mounted through a wall. The heat pump takes about 1/3 the power that resistive heat takes for the same amount of heat. Unfortunately, these small heat pumps are only efficient down to about 40 to 45 degrees outdoor temperature. Below that they use resistive heat. An Internet search found only a couple of units of the size I want (8000 to 9000 BTU/hr) that include a heat pump. I selected a 9000 BTUH Amana window unit which can be wall mounted, is 240 volt (my preference) and doesn't require a separate shroud to wall mount it, and then placed my order. It is coming cross country by truck as it was much less expensive than from local suppliers.
Between thumping the wall, using my stud finder, and refering to photos I took during construction, I managed to come up with what turned out to be a fairly accurate picture of the wall construction where I decided to mount it. It is between a door and a window, and the framing gets much more complicated in those areas.
During the summer and winter, my shop can get uncomfortably hot or cold. When I was refinishing my workbench, the shop temperature was 45 degrees. It took a couple hours of running two electric heaters to get above the minimum refinishing temperature of 55. I have been planning all along to add temperature control, but until now, I just haven't!
I want a window size unit which has a heat pump as well as air conditioning, and which can be mounted through a wall. The heat pump takes about 1/3 the power that resistive heat takes for the same amount of heat. Unfortunately, these small heat pumps are only efficient down to about 40 to 45 degrees outdoor temperature. Below that they use resistive heat. An Internet search found only a couple of units of the size I want (8000 to 9000 BTU/hr) that include a heat pump. I selected a 9000 BTUH Amana window unit which can be wall mounted, is 240 volt (my preference) and doesn't require a separate shroud to wall mount it, and then placed my order. It is coming cross country by truck as it was much less expensive than from local suppliers.
Between thumping the wall, using my stud finder, and refering to photos I took during construction, I managed to come up with what turned out to be a fairly accurate picture of the wall construction where I decided to mount it. It is between a door and a window, and the framing gets much more complicated in those areas.
header goes into the very top to support the 2 studs which will be cut out. A 2x4 across the bottom will
support the AC unit. An additional vertical 2x4 will complete the framing. After I completed this cutout,
I realized that I cannot get the trimmer studs in place to support the header. I then removed the remaining
piece of drywall down to the floor. Of course I have already removed the insulation.
The white outlet on the left is a 240 volt outlet which matches the plug type on the AC unit. I originally
installed it for my portable spot welder. I just will not have any cooling or heating during any times I need
to make spot welds! I think I have only used it once in the 15 years I have been in the house.
After removing the balance of the drywall, I was able to complete the framing.
After touching up the size of the opening I cut in the siding, the AC case slid in nicely.
I leveled, shimmed where required, allowed a 3/8 inch drop in the back for water drainage
and screwed it in place.
Since I am working alone, my hydraulic cart made the task of lifting the AC mechanism up and
sliding it into the case a breeze.
Here is the unit installed, connected, and tested out. It works! I'm glad I used drywall screws and not nails, as I just realized I did not replace
the insulation in the area under the AC. I will mask off the AC unit carefully before I do all the drywall finishing and painting.
On the right the first layer of drywall tape and mud have been applied. Looking rough here, it will look fine when done.
Home Depot did a great job of matching my wall paint, but their new paint is cleaner than my old paint.
This is the finished installation!
Stock rack
Over the years I have accumulated quite a large supply of various metal shapes and materials. The main thing they all have in common is that I have no good place to store and have access to them when I need them. I looked around my shop to see if there is a location I could build a stock rack, and decided on an 8 foot section of blank wall above my rear workbench at one end and over my grinders and cut off abrasive saw on the other. Its about the only accessible empty wall remaining in my shop. I knew I wanted strips to bolt to the wall into the studs with a number of some sort of pin sticking out at an angle. I thought of several methods, but ended up deciding to use 2x4s on the wall with possible rebar or some other steel form. I then thought of EMT electrical conduit and decided to use 6 inch lengths of 1/2 inch trade size EMT.
I bought enough 2x4s for this job and the AC installation along with three 10 foot lengths of 1/2 inch EMT. I had to cut the conduit into 5 foot lengths at the store to bring it home in my car, but when I got home, I cut up 4 of the 5 foot lengths into 6 inch pieces using a roller pipe cutter and my lathe. That made the cutting much easier than any other method I could think of and some wire brushing of the cut ends was all the finishing needed.
I wanted the finished rack to have all the pegs line up well over the length of the 6 board rack, so I made a template from an old yardstick and laid out the 6 peg holes and the 4 mounting holes on it. I drilled 1/8 in holes at each location. I then used this template (yardstick) on each board and center punched all the hole locations through the 1/8 holes. I made a quick jig from a board and a block calculated to give me a 10 degree angle. Using this under my boards, I used a wood bit I had carefully ground down to give me a press fit of the pegs into the wood. The bit had no problem following the center punch and drilling the hole, even at the 10 degree angle. I then drilled the mounting holes straight through for 1/4 inch lag bolts. Some sanding and a coat of paint made the boards ready for assembly.
Over the years I have accumulated quite a large supply of various metal shapes and materials. The main thing they all have in common is that I have no good place to store and have access to them when I need them. I looked around my shop to see if there is a location I could build a stock rack, and decided on an 8 foot section of blank wall above my rear workbench at one end and over my grinders and cut off abrasive saw on the other. Its about the only accessible empty wall remaining in my shop. I knew I wanted strips to bolt to the wall into the studs with a number of some sort of pin sticking out at an angle. I thought of several methods, but ended up deciding to use 2x4s on the wall with possible rebar or some other steel form. I then thought of EMT electrical conduit and decided to use 6 inch lengths of 1/2 inch trade size EMT.
I bought enough 2x4s for this job and the AC installation along with three 10 foot lengths of 1/2 inch EMT. I had to cut the conduit into 5 foot lengths at the store to bring it home in my car, but when I got home, I cut up 4 of the 5 foot lengths into 6 inch pieces using a roller pipe cutter and my lathe. That made the cutting much easier than any other method I could think of and some wire brushing of the cut ends was all the finishing needed.
I wanted the finished rack to have all the pegs line up well over the length of the 6 board rack, so I made a template from an old yardstick and laid out the 6 peg holes and the 4 mounting holes on it. I drilled 1/8 in holes at each location. I then used this template (yardstick) on each board and center punched all the hole locations through the 1/8 holes. I made a quick jig from a board and a block calculated to give me a 10 degree angle. Using this under my boards, I used a wood bit I had carefully ground down to give me a press fit of the pegs into the wood. The bit had no problem following the center punch and drilling the hole, even at the 10 degree angle. I then drilled the mounting holes straight through for 1/4 inch lag bolts. Some sanding and a coat of paint made the boards ready for assembly.
The six rack boards are drilled and painted, and are now ready to have the pegs inserted. The upper right of that photo
shows the future location of my stock rack, between the window and the rear wall. It also shows the concurrent
air conditioner project underway. On the right are the 36 6 inch pegs I cut from the EMT.
When I modified the wood bit to
give the exact diameter I wanted, I tried inserting a scrap piece of
EMT into a hole it made. It went well tapping with a hammer,
however the end of the peg was distorted by the blows, even though I
had hit it through a block of wood. I
needed to find a way to insert the pegs gently - by gradually pressing
them instead of using driving blows. I have an arbor press - too
small, I have a hydraulic press- too slow and too much overkill.
I then thought of trying the drill press, using it as a low power arbor
press. I made an aluminum "pressing block" to protect the chuck,
tilted the table to 10 degrees, and clamped a piece of steel to the
table to protect it. It worked beautifully! The force
required was no more than I often apply when drilling large holes and
it went very quickly and smoothly.
I am using my drill press to push the pegs into the interference sized holes in the wood. No problem at all!
I am using my drill press to push the pegs into the interference sized holes in the wood. No problem at all!
To assure that the pegs stayed
lined up during installation of the boards, I used the ceiling to
measure down to the outside, top mounting locations. Since the
ceiling is not perfectly true, I didn't want to measure all the holes
that way but instead ran a string between the two end bolts and marked
the ones in between. I then predrilled all the holes and drove in
the lag bolts using my air rachet. It would have really been a
job to drive all the bolts with a hand rachet!
On the left is my finished rack, and on the right is the rack with a load of stock to store.
On the left is my finished rack, and on the right is the rack with a load of stock to store.
Shop Oven
I have periodically needed some sort of an oven in my shop to cure epoxy, dry paint, etc. With the pending receipt of my 3D printer (yes, I have ordered a 3D printer!) I will need to occasionally dry out filament (the plastic stock used to build the items), and to recharge some desiccant used to keep the filament dry. I was looking at my counter top toaster oven and figured with some decent temperature control that it would do very nicely. Not wanting to use my present oven and then have to replace it I went thrift store shopping. At the Habitat for Humanity ReStore I saw the ugliest home oven I have ever seen. It was big and clumsy, black, and very dirty! I immediately passed it up, but then came back to look again. It looks huge, but upon a closer look, it seemed really about the same length and depth as my home oven. It is taller and looks larger, but that is because the oven is the full width of the case, instead of stopping short to allow a 4 or 5 inch control panel on the right. This unit has the controls across the top. It really met all my requirements which were to be a convection oven for even heat, and large enough to hold a reel of filament. There was no price listed so I tried to figure how much I would be willing to pay, then found a clerk. He said somewhat amazed "Can you really use this?" He then said "How about $5?" I bought it.
The first thing I had to do after getting it home and making sure the fan and heater element worked (they did) was to clean it up. It was covered with the typical dirty oven brown coating and was greasy to the touch throughout. I was going to use an oven cleaner, but checked the Internet where I found many articles basically saying to not use harsh, toxic, smelly, expensive chemicals - use baking soda. I made up a paste of baking soda and water and painted it all over the inside of the oven and the door and let it sit overnight. Meanwhile I soaked the racks in dishwater, scrubbed with Scotchbrite and scrubbies and managed to show some of the chrome. The next morning I sprayed the oven with white vinegar and started wiping it all off. It really did a good job of removing most of the brown gook, and all of the stickiness.
Here is my new ugly shop oven! I would not want it in my kitchen, but it is fine for my shop.
I thought it might be some type of commercial oven, but the rear states that it is for home use
only and not to be used commercially.
I have periodically needed some sort of an oven in my shop to cure epoxy, dry paint, etc. With the pending receipt of my 3D printer (yes, I have ordered a 3D printer!) I will need to occasionally dry out filament (the plastic stock used to build the items), and to recharge some desiccant used to keep the filament dry. I was looking at my counter top toaster oven and figured with some decent temperature control that it would do very nicely. Not wanting to use my present oven and then have to replace it I went thrift store shopping. At the Habitat for Humanity ReStore I saw the ugliest home oven I have ever seen. It was big and clumsy, black, and very dirty! I immediately passed it up, but then came back to look again. It looks huge, but upon a closer look, it seemed really about the same length and depth as my home oven. It is taller and looks larger, but that is because the oven is the full width of the case, instead of stopping short to allow a 4 or 5 inch control panel on the right. This unit has the controls across the top. It really met all my requirements which were to be a convection oven for even heat, and large enough to hold a reel of filament. There was no price listed so I tried to figure how much I would be willing to pay, then found a clerk. He said somewhat amazed "Can you really use this?" He then said "How about $5?" I bought it.
The first thing I had to do after getting it home and making sure the fan and heater element worked (they did) was to clean it up. It was covered with the typical dirty oven brown coating and was greasy to the touch throughout. I was going to use an oven cleaner, but checked the Internet where I found many articles basically saying to not use harsh, toxic, smelly, expensive chemicals - use baking soda. I made up a paste of baking soda and water and painted it all over the inside of the oven and the door and let it sit overnight. Meanwhile I soaked the racks in dishwater, scrubbed with Scotchbrite and scrubbies and managed to show some of the chrome. The next morning I sprayed the oven with white vinegar and started wiping it all off. It really did a good job of removing most of the brown gook, and all of the stickiness.
Here is my new ugly shop oven! I would not want it in my kitchen, but it is fine for my shop.
I thought it might be some type of commercial oven, but the rear states that it is for home use
only and not to be used commercially.
I ordered a low cost import digital
controller from Amazon. It is amazing! It displays both the
current temperature and the set temperature, allows Celsius or
Fahrenheit, allows you to tailor the actions to your needs, and was
under $10! I worked out the existing wiring diagram of the oven
and modified it to incorporate both the controller and a master power
switch. I don't like the idea of trusting a spring wound timer to
positively turn off the oven. When I had time after finishing the
projects listed above, I incorporated both the master switch and the
controller. I then somehow figured how to put the various panels
and covers back together and inserted dozens and dozens of sheet metal
screws.
It looks like it should make a good, low temperature shop oven. Even though the original oven went to 450 degrees F., this controller only goes to 230 degrees. That should do all the currently planned tasks. If in the future I need it to go higher, a higher priced controller can be incorporated very easily.
And here is my completed shop oven in its new home on my rear workbench.
OK, it's a few days later and I decided to redo the oven! It bothered me that I was so limited in temperature and trying it out after I completed revision #1, I found I didn't like the way I had the switches set up. The timer was worse than useless as was the Convection/Broil switch. It originally turned off the fan and turned on the heating element full time, bypassing the thermostat to broil your meat. It didn't bypass my added controller, but I never want to turn off the fan if the oven is on.
I decided to upgrade the controller and to totally re-do the switching system. I removed the timer and moved the master power switch to its location, I re-purposed the Broil switch to disconnect the heating element. This allows me to keep the fan running during cool down with no chance of the heat coming back on as it cools. The fan runs if the main power switch is on. I left the original thermostat in the circuit as extra protection. If something happens to the main controller, the thermostat will limit the temperature to its setting, which I will always run a little higher than the main setting.
In looking at controllers, I kept coming across the term PID. I finally Googled it and found out it is a much more precise type of controller. Instead of merely switching the heater on or off depending on the current temperature, it anticipates and calculates three different terms to decide when to switch on or off. I won't try to explain in detail (partly because I don't really understand it myself), but a quick quote from Wikipedia says "A proportional-integral-derivative controller (PID controller or three term controller) is a control loop feedback mechanism widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value as the difference between a desired setpoint and a measured process variable and applies a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively) which give the controller its name." OK, now you know more than I do about it.
In short, I bought a PID controller that wasn't really that much more expensive than my first simple one. Instead of having a built in relay to drive the heater, this has an external solid state relay, partly because it is just higher quality, and partly because part of its control involves rapidly turning the heat on and off to modulate it, and a mechanical relay would not hold up well to that type of service. It did cause me a couple of problems however: The old controller was about an inch deep from the front of the panel, this one is about 3 1/4 inches. The solid state relay is only a little over 1/2 inch thick, but it mounts on a 2 plus inch heat sink. There is no place in the oven suitable for mounting either of these! My solution was to remove the left hand sloping panel and replace it with a right angle piece of plastic, giving me a vertical mounting surface. This provided a rectangular cross section large enough for both items. Moving the power switch to the right panel provided plenty of room for the wiring.
The new controller will control temperatures that are much higher than this old oven can reach. Using a thermocouple instead of a thermister, it can control from -100 to +2300 degrees F. I don't think I have a problem with my lowly 450 degrees F on this oven.
I have finished putting it all together, re-wiring it, and making sure it all works correctly. I have not done any testing to see how well the control works and whether I need to "tune" it. There are variables that can be changed to tailor the control to the properties of the item it is controlling. There is an auto tuning function that is supposed to get it close. If not there is a lengthy procedure to accurately set it up. Hopefully the auto tune will be fine.
This is now what my oven looks like. The added right angle plastic on the left provides enough room
for the controller and the solid state relay with its heat sink. In operation, there is very little overshoot
of the temperature (1 to 2 degrees) at startup, and a very precise, steady control after that.
It looks like it should make a good, low temperature shop oven. Even though the original oven went to 450 degrees F., this controller only goes to 230 degrees. That should do all the currently planned tasks. If in the future I need it to go higher, a higher priced controller can be incorporated very easily.
And here is my completed shop oven in its new home on my rear workbench.
OK, it's a few days later and I decided to redo the oven! It bothered me that I was so limited in temperature and trying it out after I completed revision #1, I found I didn't like the way I had the switches set up. The timer was worse than useless as was the Convection/Broil switch. It originally turned off the fan and turned on the heating element full time, bypassing the thermostat to broil your meat. It didn't bypass my added controller, but I never want to turn off the fan if the oven is on.
I decided to upgrade the controller and to totally re-do the switching system. I removed the timer and moved the master power switch to its location, I re-purposed the Broil switch to disconnect the heating element. This allows me to keep the fan running during cool down with no chance of the heat coming back on as it cools. The fan runs if the main power switch is on. I left the original thermostat in the circuit as extra protection. If something happens to the main controller, the thermostat will limit the temperature to its setting, which I will always run a little higher than the main setting.
In looking at controllers, I kept coming across the term PID. I finally Googled it and found out it is a much more precise type of controller. Instead of merely switching the heater on or off depending on the current temperature, it anticipates and calculates three different terms to decide when to switch on or off. I won't try to explain in detail (partly because I don't really understand it myself), but a quick quote from Wikipedia says "A proportional-integral-derivative controller (PID controller or three term controller) is a control loop feedback mechanism widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value as the difference between a desired setpoint and a measured process variable and applies a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively) which give the controller its name." OK, now you know more than I do about it.
In short, I bought a PID controller that wasn't really that much more expensive than my first simple one. Instead of having a built in relay to drive the heater, this has an external solid state relay, partly because it is just higher quality, and partly because part of its control involves rapidly turning the heat on and off to modulate it, and a mechanical relay would not hold up well to that type of service. It did cause me a couple of problems however: The old controller was about an inch deep from the front of the panel, this one is about 3 1/4 inches. The solid state relay is only a little over 1/2 inch thick, but it mounts on a 2 plus inch heat sink. There is no place in the oven suitable for mounting either of these! My solution was to remove the left hand sloping panel and replace it with a right angle piece of plastic, giving me a vertical mounting surface. This provided a rectangular cross section large enough for both items. Moving the power switch to the right panel provided plenty of room for the wiring.
The new controller will control temperatures that are much higher than this old oven can reach. Using a thermocouple instead of a thermister, it can control from -100 to +2300 degrees F. I don't think I have a problem with my lowly 450 degrees F on this oven.
I have finished putting it all together, re-wiring it, and making sure it all works correctly. I have not done any testing to see how well the control works and whether I need to "tune" it. There are variables that can be changed to tailor the control to the properties of the item it is controlling. There is an auto tuning function that is supposed to get it close. If not there is a lengthy procedure to accurately set it up. Hopefully the auto tune will be fine.
This is now what my oven looks like. The added right angle plastic on the left provides enough room
for the controller and the solid state relay with its heat sink. In operation, there is very little overshoot
of the temperature (1 to 2 degrees) at startup, and a very precise, steady control after that.
GO BACK TO "Machine Shop Projects"
R. S. Mason
March 2018