Category Archives: Tool builds improvements and repairs

Simple Jig for Hand Sharpening Planer Blades

Sharpening planer blades by hand    Every serious woodworker has a thickness planer in their shop.  The best lumber is often sold rough, allowing the craftsman to plane it down to the perfect thickness without having to worry about getting nicks or scratches in the surface while storing/transporting it.  Since I have been milling my own lumber I rarely buy wood but all of my wood needs to be planed smooth to thickness.  This has resulted in significantly more wear on my thickness planer blades and an increase in frequency to my sharpening the planer blades.  To help with the sharpening chore I built a hand sharpening jig out of stock I had in the materials bin using my CNC Milling machine.

13 planer blade sharpening jig-2134    My planer blades are 13.5 inches of double edged sharper then a razor tool steel about 1/8″ thick. I found the best way to handle, move and store them between the planer and sharpening is by attaching them to a bit of scrap wood.  This eliminates any chances of accidental cuts or chipping the cutting edges.   After a couple hundred board feet of lumber goes through the blades need to be honed to allow for perfectly smooth surfaces on the boards.  As the edge dulls or worse gets a nick, it leaves raised marks and imperfections along the length of the lumber as it passes through the thickness planer.  It can be surprisingly hard to remove the marks left on the surface by sanding, making regular sharpening of the blades a must.

Hand sharpening planer blades  The sharpening jig I designed and built is pretty simple. I believe my original idea came from something I saw in Woodsmith or Wood magazine years ago.  In the past, it was reasonable to have my planer blades professionally sharpened (~$15 a pair)  or purchase (~$30 a pair) but today with rising prices (almost 50 bucks for sharpening and 90 for new blades) coupled with the increased frequency I need to sharpen them I can not justify the cost.  The jig consists of a bearing mounted on the end of an adjustable arm that allows for changes in the sharpening angle.  The arm is attached to the body which is essentially a stiff clamp that holds the blades parallel using two dowel pins for alignment.

How to sharpen 13 inch planer blades    13 planer blade sharpening jig-2133

The above left photo shows the clamping piece,  it’s machined flat where it clamps down on the blade.  In addition the center is milled out so all of the clamping force from the machine screws goes onto the center of the blade. This is an important feature.  If you use a piece of unmmachined flat stock you risk having your planer blade rocking or being loose during sharpening.

a simple jig for hand sharpening planer blades

The above close up photo shows the blade clamped in the jig from the end.  You can see the milled slot and how it functions to hold the planer blade completely flat against the other half of the jig.

13 planer blade sharpening jig-2132      13 planer blade sharpening jig-2135

For a sharpening surface I’m using a piece of mirror polished Marble I had left over from some restoration work I helped a friend in Beacon Hill with a couple years ago.  It’s a hard flat surface.  I’m using wet or dry sand paper and emery (for the rougher treatments) to sharpen the blades on the marble slab.  Turned diagonal a standard sheet of sandpaper is wide enough to allow me to sharpen my 13.5″ planer blades.  Use plenty of light oil or WD40 to keep the metal particles from clogging the paper.

How to sharpen 13 inch planer blades     13 planer blade sharpening jig-2137

After careful initial setting of  the angle by adjusting the length of the bearing arm,  sharpening is simply a matter of olling the blade forward and back across the paper with light pressure.  This method takes 10-15 minutes of time  but the results are spectacular.  I usually go from 120 up through 800 grit paper when sharpening my edges.   As I have only used this jig for my longer planer blades to date, after the initial angle setting I have not had to change the angle again and a resharpening goes quickly.  I may make a second smaller unit for sharpening my 6 1/4″ jointer blades in the near future.   This handy little jig cost me nothing, as I made it from materials on hand, and has been used numerous times to quickly sharpen my blades saving me the time and expense of sending them out to be sharpened.

Low cost PID control box for heating/cooling

Assembling a PID temperature control box-1795

One of the joys of the modern world is the availability of low cost PID temperature control modules.  These have been around for a long time in the industrial world but in the past were cost prohibitive for home hobby use.   Now you can buy a pid temperature controller for $25 from Amazon.com.   Adding  in a type K thermo couple ($6),  a 25A SSR ($7) , and some items from your parts bin (switch, outlet, plug, fuse holder) you can build a nice little temperature control panel capable of keeping a piece of production equipment at a fixed temperature while running for less then $50.

Assembling a PID temperature control box-1793   Assembling a PID temperature control box-1792

Only basic instructions are included with the controller, if you aren’t familiar with set up and tuning search the web

This project is more for documentation for future use by myself but here is some back story.  I was in need of a temperature control unit for a piece of production equipment for my company.  We had purchased a cheap control unit that was essentially a solid state pulse width modulator, ie. turning the device on and off  with control of the cycle times.  During production runs the PWM unit did not keep the temperature fixed and we were seeing variations in the final quality of the product.   This is a low risk, non hazardous process and so this quick cheap but very accurate PID temperature controller was the way to go.

***  Disclaimer – I would not use parts of this cost/quality when working on a chemical process or a piece of process equipement where a failure of temperature control would result in something bad happen such as a run away reaction or explosion.  ***

Assembling a PID temperature control box-1787

The wiring is fairly straight forward as shown in my rough, chicken scratches on paper diagram above.  I’m not proud of the drawing, but it was more for the dimensions of the switches then the actual wiring diagram.   I used my cnc machine to mill out the panel that houses all of the components. (dimensioned drawing of panel – PID Temperature Control Panel Drawing)  You could just as easily hand cut openings in a small electronics box if you were building one at home.

Assembling a PID temperature control box-1790   Assembling a PID temperature control box-1791

Be sure to carefully follow hook up instructions on the PID temperature controller.  The unit has makings labeled (Note:  the part numbers in the above picture are for future my reference) on it as well as in the instruction sheets.  These were taken during the first assembly. I have since added a fuse holder between the line in and the switch with an appropriately sized fuse for my device.  Fuses are important as they protect your equipment in the case of a failure.

Assembling a PID temperature control box-1789   Assembling a PID temperature control box-1794

When you wire up projects like this, take time to do a tidy job of it.  While as a hobbiest we do not have 100 colors of wire to choose from, make choices that follow standards if you can.  A few I always keep are white is for neutral and green is for ground in any AC wiring.  Standards are there for a reason. I recently worked on something where the manufacturers chose black wire to be the V+ and green the  V-.  It was nothing but a headache to work on so choose your wire colors appropriately, you might need to go in and add or change something in a few years and keeping to standards makes life easy.

Assembling a PID temperature control box-1788

The finished PID panel works and looks great. It resulted in a significant decrease in reject rate on our production (15rejects/1K reduced to 1 reject/1K). I will build a second identical PID temperature control unit  to run my filament extruder that I am working on building to feed my 3d printer using recycled scrap plastic.

A quick easy way to make an XL series timing belt mount

XL timing belt mount

Timing belts are useful for all sorts of synchronous motion.  They can be used to connect a rotary encoder to a lathe spindle or to provide linear positioning on a 3D printer.  They have little stretch or flex and can accurately transmit rotational motion.   One of the challenges with using timing belts is mounting them in your projects.  This is especially true when you want to use timing belts to convert rotational motion of a computer controlled stepper motor into positionally accurate linear motion on a project like my 3D printer build.  Here’s a fast and easy way to make yourself a timing belt clamp and mount for your project.  The clamp shown in this post will function as the y axis mount on my DIY 3D printer (photo installed at the end).

how to make a timing belt clamp using hot glue-1645

Any craftsman, maker, car guy, or project loving person knows about and owns a hot melt glue gun. They are good for many things,  in this project the hot melt gun is going to provide the plastic uses to pattern our timing belt interlock features on a substrate.

how to make a timing belt clamp using hot glue-1648    L series timing belt clamp

Wear gloves when playing with hot things!

First you need to make a mounting block for use as a substrate from your material of choice.  Aluminum in this case.  I machined the part to fit onto my 3D printer’s y-axis structural cross member.  I cut a small scrap of XL series timing belt to fit the groove. This is why it is always good to hold onto things like a scrap bit of timing belt.  It may be hard to see in the picture above but I drilled a series of 6 shallow holes into the timing belt slot to allow the molten hot glue to seep in and form mechanical interlocks.  It’s best not to rely on the adhesive strength of the hot glue, mechanical interlocking features for the polymer to mold into provide good shear resistance.

Pre-heat the substrate.  You could use a project toaster oven,  heat gun, 500w lamp, etc.  I used the woodstove.  If you try this with a cold substrate the hot glue will cool too quickly to mold to the features of the timing belt. You want the substrate warm so it does not pull heat out of the molten polymer before we can mold it to the timing belt.

XL series timing belt mount using hot glue - 7

Quickly take your preheated substrate from your heat source, put it on a nonflamable surface (leather glove in this case) and fill both sides with hot glue quickly.  Use a bit more then you think you need, it will seep out the ends if there is too much in the slot.

XL series timing belt mount using hot glue4

Then clamp down the timing belt into the molten plastic with the screw. I used a long screw to provide alignment and a nut to make clamping  easier and faster.  It is also acceptable to just squish it down with your fingers.   Put the hot assembly into cold water to quickly cool the hot melted plastic before it can seep out of the cavity.

XL series timing belt mount using hot glue

Let it cool completely before disassemble.  I’ve never had any issue with the hot glue sticking to the timing belt enough to be a problem.  Usually it is possible to remove the Timing Belt used to mold the plastic with fingers. If it is a bit stubborn in coming free use a small pair of pliers to get a grip on the bit of timing belt and slowly pull it up and away.

XL timing belt mount

When disassembled, trim up any of the plastic that seeped out with a sharp exacto knife or chisel.   As you can see you get a perfectly molded Timing Belt clamp that can be used for your project.

XL series timing belt mount

Here’s the finish timing belt in place on the 3D printer project.  The stepper motors have 10 tooth pulleys on them to drive the XL series timing belts allowing the y axis to move with positional accuracy.  More on the 3d printer progress as I have time to write.  It is nearly operational!

 

Converting a wood bandsaw into a metal cutting bandsaw

bandsaw conversion metal cutting

I needed a small metal cutting bandsaw for pre-cutting stock for my 3 axis CNC milling machine but I did not want to spend a lot of money on a new one.  I had been checking craigslist when this little gem came along.  It’s a Rockwell/delta 10″ bandsaw (here’s a copy of the owners manual for this saw) that  takes a 71 3/4″ blade.  It has a nice rigid cast iron frame, metal band wheels, and an open drive mechanism making it perfect for a conversion.   The major difference, outside of the blade itself, between a wood cutting bandsaw and a metal cutting bandsaw is the blade speed.   Wood cutting bandsaws run too fast for metal cutting.  To convert over to metal cutting duties I needed to reduce the speed of the band wheel by about a factor of ten.

bandsaw conversion- gear reducer   Band saw conversion metal cutting

My initial inclination was to use a larger pulley to slow down the blade but some calculations determined even a double pulley reduction would not slow it down as much as I would like.   I went through my list of parts on hand and decided to employ an EPL series motion control gear reduction unit with an 8:1 reduction ration.  That would slow the bandsaw blade down with the pulleys I had on hand to a good speed for cutting metal.

Making a spindle- metal cutting bandsaw conversion    metal cutting bandsaw

The gear reduction drive is designed to bolt onto a face mounted motor and as such has a female shaft mount on one end.  I quickly turned a spindle from some steel stock to 24mm on the gear drive end and 5/8″ on the other for the pulley.  The goal of this project was to quickly have a good metal cutting bandsaw with what I had on hand and minimal spend.   Coming back to the discourse on design, I was designing with what I had available for this project.  It may seem a bit ridiculous to use such an expensive part on a $50 saw but I figure I can always pull the gear reducer later if a more pressing need for it arises.

 DIY metal cutting bandsaw   DIY metal cutting bandsaw conversion speed reduction

I decided to reuse the original belt that came with the saw.  I upgraded the stock pulley to the largest one I had on hand, and drilled some holes into the legs of the stand to mount the reduction drive.  The gear drive needed a bracket to support it on the other end.   One was fabricated out of 1/8″ steel stock.   This arrangement required the motor to be relocated which was accomplished by drilling 4 new holes in the correct location on the base of the stand.  Be sure to check the motor rotation and reverse it (usually swapping wires inside the motor wire box) to correct it if the blade is going the wrong way.

bandsaw conversion   how to convert a wood bandsaw to metal cutting

The new drive belt is a 4L290, as I happen to have 3 of them on hand.   I only had to buy 2 parts in addition to the bandsaw itself for this project.   The first was the small pulley that is mounted on shaft of the gear reduction drive.  I purchased a 2 3/4″ dia pulley with a 3/4″ bore at my local tractor supply store.  Tractor supply has a good selection of motors, pulleys, and belts in stock.  Not a lot of hardware stores carry these items in this day and age.   I had to bore out the pulley’s 3/4″ bore  to 20mm on the lathe to make it fit onto gear reduction unit output shaft.

Wiring on old tools is horrific and when I opened the electrical box up I was thankful I didn’t get electrocuted when I tested out the saw.  I replaced all of the 40 year old scary wiring and upgraded the switch with a modern unit.

Wood bandsaw to metal bandsaw conversion     Reducing the blade speed on a wood cutting bandsaw

The only other part I purchased for this project was a small spacer for the handybox that encloses the wiring for the bandsaw.  These are available at Home Depot for less then a buck.  The new switch I selected did not fit in the enclosure, requiring the spacer.  I used the CNC mill to cut the opening in the switchplate.

The finished tool works well and I’ve already cut several linear feet of aluminum stock on this saw, with a 6 tpi wood blade in place.  I’ll be ordering up some good bi-metal blades in the near future.  I am very happy with this little project and foresee myself getting many years of good use out of this saw.