Construction Tips and advice From Members

Good ideas on how to do certain operations in engine building that may not be obvious in the beginning.


TIP 1 6/17/2002

Digital Depth Gage - Dale Detrich - []

On the Smithy , all that I did was make a new stop collar on the mill quill (replacing the original , which was plastic) and I drilled and tapped a threaded hole to install the bottom mounting pin. At the top pin location , I replaced a bull nosed set screw which holds the quill from turning. I replaced it with a short length of metric all thread, finishing the pins with flats to mount the caliper to. The caliper is held to the pins with 2-56 screws, the clearance holes in the caliper are drilled with almost zero clearance for a 2-56 screw( to prevent slop). Two things that you must check before mounting the caliper. First - make sure that the flats on the pins are parallel to each other, (so it does not bind the caliper when you mount it to the pins. Second -- the quill travel has to be less than 6 inches so you do not over extend the caliper... You may need to change the mount to fit you own needs, and machine. The price of calipers is almost nothing, and I have had my caliper in place for aprox. 6 years with no problems.


TIP 2    9/11/2002

Poor man's diamond wheel - Dale Detrich - []

I bought a diamond wheel made to be used on ceramic tile , at a flea market for $2.00 ea. ( I bought about 10 of them ) . And on my bench grinder I made a hub that both held the regular wheel and has a shouldered hub to hold the diamond cut off wheel, so it runs true.. The diamond wheel runs backed up by the regular wheel, and when you use the diamond wheel you are grinding on the side of the regular wheel.. You will have to make a new tool rest at the side of the grinder to rest the tool that you are grinding on.. I have used the same wheel for about 5 - 6 months and it is still good, also the wheel that I have has a diamond surface on the back side of the wheel , so it can be reversed and used the second time.. The diamond wheel area is aprox. 5/16" wide, not great but ok for most small tools.. I have the second tool rest removed to take the pictures.. Any questions please contact me


TIP 3    11/12/2002

Propane Demand Regulator - Richard Williams - []

I give the plans for the demand regulator out free to my fellow modeler's.    Using propane you will need to enlarge the fuel orifice. For instance if you have a hole for gas .040 propane would be .060 to .080.  Also you may need to make the intake hole on the carb smaller to pull more vacuum.  A easy way to check this is to put a piece of masking tape over the intake on the carb and put a small hole in it.  If the engine runs to rich, enlarge the hole.  When you can control the fuel with the needle valve, about two turns open the hole is just right.  Take the tape off and measure the hole then put a bushing in the carb with that size hole.  The only other thing on the demand regulator I think the drawings say to use a regulator on the bottle. 

Click here to down load the drawing as an Adobe PDF file you can print

Mike Neal met Richard at PRIME and Richard has since joined FAME.  I have been looking for information about running model engines on propane for nearly 2 years.  I am concerned about exhaust gasses in the air conditioned shop.  As soon as I build one I will add a picture.  David

11/14/2002 Update  from Richard

I don't have a single regulator, mine is a piece of aluminum bar stock which is 1 "x 2" x 9" with four regulators built in a row.  This is what I use at shows and I can run four engines at one time.  You can make these as long as you want, you just drill the inlet hole all the way through and tap and plug one end.  When I made mine I left about 3/16 to 1/4 inch between the tops.  You may want to drill in from both ends because drilling that far the drill wants to go crooked.

When I measured it is1" x2.500" x 9", that is the piece of aluminum that I had on hand at the time, but the measurements you have are correct. You might state that the one in the picture is wider than it should be.  Also you may add that you can run one engine at a time or four at once.  Richard
11/18/2002, I got a email on the demand regulator wanting to know how it worked.  It probably is hard to understand without the parts.  Once you have the parts there is only two places they can go.   I have made a quick drawing on how it works.  Richard
  12/29/2002  I have wanted to use propane as fuel for years so I had to build one, and had problems.  The helpful advice from Richard is provided below.  David
12/22/2002  I am not sure whether the engine you are having trouble with is a throttler or a hit and miss.  If it is a throttler you will need to open the needle valve more as the engine runs faster.  Yes the length of hose does make a difference.  I use .093 model airplane silicone tubing two feet or less is ideal but when you use for instance four feet you will need to open the needle valve a lot more.  The regulator you are using sounds ok, if it has low medium and high turn it to high.  A good pressure gauge is nice to have, because if the reg is on low it may not be enough fuel and the gauge will show that.  The smallest bore engine I have is a 1/2" bore and the largest is 1-1/2" bore and they run on the demand reg fine.  I had one two cylinder with 3/4" bore that ran at 5,ooo RPM on the reg so I know they are capable of working at high speeds.  Take the hose from the outlet of the demand reg and put it in water to see if it is leaking, some times this causes a problem.  Because it will give the engine enough to start on but not to run on.  It will usually flood a hit and miss, while the engine is coasting it will have too much fuel at the carb if the demand reg is leaking.

One other thing you might check is the rubber seat that the needle seals against, I have found these tipped to one side.  I take the back of a drill or something similar and push on it to seat it.  I ground a end mill specially to use for the 3/8 hole, this gives you a flat bottom for the gasket to seat on.  You can use a little silicone on the gasket to seal it, I have done this and it works good.

When you said it would almost run when the reg was leaking, that tells me it is not getting enough fuel.  There could be two things happening here, either the spring has two much pressure under the needle; but if the reg is built per drawing it should be ok.  The other thing is the intake on the carb is to large and not pulling enough vacuum to pull the diaphragm down.  Put a piece of masking tape over the carb and put a small hole in it about .062 and try it.  The needle valve hole will need to be some what larger for propane.  Once you get it to run you can experiment with making the hole larger in the tape.  Then when it runs to suit you make a bushing the size of the hole in the tape and put it in the carb.  I made two regulators the other day, both are identical made by the drawings.  When I tested them before I shipped them I did it on a 3/4 bore engine.  The first one ran it fine, the other one wouldn't run it, took it apart & couldn't find anything wrong.  So I opened the needle valve one more turn and it ran fine.  I have the diaphragm on the body and the gasket on the lid. 



TIP 4    11/22/2002

Make your own miniature hinges - Gary Hart   -

Take the hinge pin diameter add twice the thickness of material you are using and add a little more to this for clearance.  This will be the drill size to use for drilling a hole in a hunk of steel that is as wide or a little wider then the hinge you want to make.  Then cut a slot that will enter the drilled hole on one edge as illustrated.  Brass shim stock is good material for making hinges and I found it works best if not annealed.  Clamp the brass shim stock in your smooth jawed vise so as to not mar your material.  With enough material sticking up to form about 1/4 to 1/3 of the curl.  Place the tool over the material with the material in the slot, hammer down on the end of the tool. If too much material is above the vise there might be a tendency to buckle the material. .  Raise the material up and repeat until the material has curled back on itself.  If the material wants to make a sharp bend rather then follow the curve of the hole,  insert your hinge pin before the loop is completed.  Make the other mating part of the hinge and cut out the unwanted sections with a fine bladed jewelers saw.  Hinges usually have odd number of loops with the most loops going on the stationary part of the hinge.          


I often have problems finding small hinges and clasps for small boxes for batteries or ignition parts and this is an interesting method.  David


TIP 5    2/19/2003

Long Reach Drill Bits - Clif Roemmich   -

For many years the longest drills in my shop were jobber length. When I had holes to drill that did not require drilling deeper that the length of  a jobber drill but required a long reach, I would lengthen the bit. To lengthen the bit I would use a piece of steel rod 1/8 of an inch larger in diameter than the bit. The rod was chucked in the lathe, center drilled and then drilled 1/2 to 3/4 inch deep using the bit to be lengthened. The next step is to coat the inside of the hole in the rod with super glue. Then insert the bit into the hole, use caution and a rag around the hole to prevent the super glue from squirting out, possibly into your eyes. Allow the glue to set at least 5 minutes. I have used this method to lengthen bits up to 1 inch. With a good fit and a good coat of glue , the joint will hold up to the most rigorous drilling. After use, the rod and the bit can be separated by heating the joint with a propane torch. As you are heating attempt to pull the two apart so that you apply only the heat necessary to release the glue. Beware! heated super glue has nasty fumes, use good ventilation. Happy deep-reach drilling!       Clif Roemmich     Piedmont, SD



TIP6    1/24/2004

Indexer - Dario Brisighella


The last time I ordered gears for my engine, I was very disappointed with the diameter of the hub
on the smaller gear. After boreing it to fit the crankshaft, there was little stock left for set screws
let alone a keyway. Having the gears on hand, I decided that it couldn't be too difficult to duplicate
them if I only had something to hold the original gear and the new blank steady as the teeth were
generated at the mill. The tougher part of this undertaking was grinding a tool bit to fit the original.
Most of the bit grinding was done at the bench grinder, with the final finished bit was ground with
my Dremel Tool. Some years ago I remember a similar indexer in a friends shop and set out to build
the indexer you see here. The photograph shown is almost self explanatory. The actual size here
is only dependent on the size of the gears you wish to produce. The most important thing is that
the central shaft be well supported. I used a pair of ball bearings that I had but close fitting sleeve
bearings would work just as well. I found a great little program at the W.M. Berg site that is free
to download Its called "GearSpec" . You select the diametral pitch and number of teeth and the program outputs the information needed to produce the gears. I didn't build the indexer to save a few dollars but, rather to insure hub sizes that suite me better and I need not wait for ordered gears to arrive, besides, its another challenge that's' not too difficult..


TIP7    1/24/2004

Indexer - Dario Brisighella


I hate to have to get out my rotary index table and set it up etc., in order to layout for example:
bolt holes on a prescribed bolt circle. I made up this little device that saves me the

Fig 1

As pictured (Fig-1), I have a small aluminum tool holder that is fitted with a hardened
and pointed dowel pin as the scriber. To insure that the pin is on the true centerline of the
lathe, The aluminum portion was mounted in the tool holder and the hole for the scribing pin
was center drilled using the rotating lathe chuck and to also do the actual final drilling.
With the scribing pin in place in its holder, the scribing pin is chucked

Then the tool post is moved into position to hold the scriber while the pin itself is still locked
in the chuck

 Now open the chuck jaws and the cross slide of the lathe can be
moved the required distance and the bolt circle can be scribed

The actual bolt circle need not be scribed onto the work piece as show here,
as the pin can actually be used as a center punch, using a soft faced hammer
etc. to tap the end of the pin. The OD of the work piece can also be scribed

The key to all of this is the scriber and an inexpensive drafting protractor

 Mine adapts to the backside of the lathe spindle and I have a simple pointer attached to the
gear case cover of the lathe. I think you will find all sorts of other uses for this small gem,
as I have.....and it only takes minutes and scraps to build.....


TIP8  2/16/2004

 POOR MAN'S DRO - Dario Brisighella

While my Maximat V-10 Lathe and mill have served me well for the past 28 years, I felt it was time
to upgrade it a bit. I did some site checking and didn't feel that it was worth hundreds of Dollars
to install the three-axis, remote reading fancy Digital Read Out that are available. Searching a bit
further I ran across some really inexpensive Digital Read Out Scales, that can be easily mounted
to most any axis, as they are available in many lengths. I purchased a 12 inch vertical mount unit
for $50.00. (these are available for horizontal or vertical reading), to mount on my mill head (the "Z"
axis to start with). Besides the calibration on the mill handwheel has been driving me a bit crazy
ever since I bought it. That calibration is .0625" per revolution, all the others are .100" per rev.
These units came with mounting brackets and its no big deal to fabricate new ones that will work
better for the installation. As shown in the photograph, the read portion is quite similar to the
better known Digital Calipers. I don't think I spent more than an hour to mount the unit and am
very pleased with it's operation. So pleased, that I ordered a much longer Horizontal reading
unit for the lathe carriage (the "X" axis). Installing a unit for the "Y" axis on the lathe carriage appears
to be a bigger challenge on my lathe and I worry about the chips and oils etc., fouling the scale or
the Digital Head but, I'm thinking? Check out: you may start thinking yourself.


TIP 4/20/2004

 More POOR MAN'S DRO -    Tom Ziebold


These are pictures showing a digital caliper mounted in three different positions on my Sherline mill. I suppose I could have invested $59.97 and mounted three calipers at once, but in fact they sort of stick out and get in the way on the X and Y drives. So I have opted to move them as needed. It only requires changing two 4-40 screws to move a caliper.

Drill holes in the caliper faces with a carbide bit to clear closely a 4-40 screw (#32). Mount small aluminum blocks on the mill bed as needed for correct alignment of the fixed arm of the caliper, and tap 4-40 holes in the moving bed or carriage and the stationary base. I cut off the tips of the caliper gauging faces and also the depth rod extension because they get in the way, but this is not really necessary.

Make sure the caliper is mounted parallel to the motion so that there is no binding. It's easy to check calibration against the handwheel scales. Sure beats counting rotations of the handwheel.

Tom Ziebold, St. Petersburg

TIP10  4/6/2005

 POOR MAN'S Ball Truning -   Jan Trollerud, Norway

This is a picture of a poor mans ball turning attachment. It works very well. Max Diameter is 30mm but this can easily be increased, I am not including any measurement... the pictures say it all.

TIP11  7/14/2005

 Casting at home -   Hank Helmen,     Ruckersville, VA

Click here to see more about how Hank makes his castings at home.

Tip12               12/12/2005

Digital Tachometer  -  Kamran Nili    []

This is a digital tachometer the full circuit and programming on the micro computer can be seen by clicking here. 

Tip 13       7/7/2007

Tapping Tool,  Jan Trollerud

A tapping tool for small taps.  Click here to see drawing.


British Associated (BA) Taps

 Clearance Drills & Conversion to US Taps

BA Size

Clearance Drill

US Tap Size Equivalent








































 Clif Roemmich




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