This tutorial is following the one made by Joe Grice that you will find just below this article. This presents different techniques from the one used by Joe. The result achieved with my techniques will be slightly different. The panel lines will be more pronounced and the general aspect of the aircraft will be rougher.
1. Aircraft preparation
One nice thing with Flite metal is that it sticks better to mirror finished surfaces. So I usually just wipe the whole aircraft with an acetone dipped cloth to get rid of the demoulding wax. Then I fill the original rivets with a thin layer of 3M Acryl Green putty. This putty is very thin and very easy to sand. I make sure the rivets prints would still be visible after the covering process to punch them in again easily.
One wing in preparation.
The nose section being prepared.
I carefully vacuum clean the sanded areas with the brush adaptor and then wipe again the whole surface with acetone.
I then prepare the few areas that will be painted without Flite metal ( fin, nose and the area below the stabilizer ). Not covering the painted areas will save weighgt. However if you decide to make paint chipping s that reveal the underneath aluminium surface, then covering with Flite MEtal will be much nicer. Once again, I use acetone to remove the wax, then sand and prime. I use Warbirdcolors primer and sand it with medium grit 3M sanding pads.
2. Aircraft covering
The Flite Metal foils are not too difficult to put down but require a little bit of training. For the first timers, I'd recommend ordering 30% more material as you will find necessary to remove the patches a few times before you achieve a proper result.
Flite Metal web site is nicely documented and Ed usually ships the rolls with a set of covering instructions. If you stick to these instructions you’ll be on the right track to do a pretty nice job from the first shot. However I’d like to give a few recommendations.
- Use the appropriate tools: I use exclusively 3M dry sanding pads and sponges and good quality drawing/ smudging pens ( burnishing tool ).
A selection of the used tools: Hole punchers, 3M sanding block and papers, steel wool pad, 3M medium and fine sanding pads, large and medium smudging pens, 3M green and grey sanding sponges.
- Start with easy flat areas. If you mess up, do not wait too long to remove the film or the glue will set and removing the foil will get much more difficult.
- Once the foil has stuck to the surface, do not try to re-fit it because you’ll stretch the material and get wrinkles. Therefore, the initial tacking is very important.
- Prepare each patch carefully. You’ll have to cut them about 1” bigger. Once the patch is cut you will have to “work” it before applying it. This step is very important since it will make the aluminium much softer and less prone to wrinkling. Simply put it on a clean cutting mat and sand it with the provided 3M green sponge on both directions. The foil has to get flat dark grey. Note that this color will change when you will sand it again after the covering.
It seems that doing this softens both the aluminium and the backing paper. The foil will then be more flexible and easier to apply.
Here is how a prepared foil should look like: dull dark gray.
- If you are getting some wrinkles, you can erase them by carefully “ironing” the aluminium surface down with a thin metallic ruler ( you’ll have to smooth out the ruler tip first with 400 grit sanding paper to get it less aggressive )
- Cutting the patch: always use a sharp new blade. Dipping it into mineral spirit before the cut will lubricate it and avoid tearing the thin aluminium foil. It will also help separating the glue coat which is soluble in mineral spirit.
Here are a few additional tips and techniques depending on the area to be covered:
2.1. Flat areas
I like to start the flat areas from one edge of the aluminium patch. It is less tricky than starting from the middle since you won’t have to bend it dimensionally. I use the hinging method to place the foil. I place the sheet with its backing on the area and center it. I tape it on one side with low tack paper tape.
Step 1: I use low tack 3M masking tape to hinge the patch
I then lift it and remove the backing from the hinged side by about one inch. I then stick it back to the surface while working it with the burnishing tool. After ½ inch is done I remove the hinging tape, get rid of the possible bubbles and carry on the same way.
Step 2: removing the backing paper by about 1 inch.
The initial tacking of the aluminium is very critical for the rest of the operation, because you don’t want to introduce any foil warping at this stage.
Step 3: tack the aluminium gently.
I remove the backing paper gradually as the work progresses. This will help you a lot in holding the unstuck part of the foil. It will also support it if you need to apply some tension while working it out. Make sure you don’t lift the foil up by more than 30° when you hold it during the burnishing process, or you might get wrinkles.
I hold the foil and pull the backing paper with one hand. This gives just enough tension while burnishing it. Note the low foil angle.
Burnishing the aluminium: proceed with gradual passes. Changing the burnishing motion will help getting rid of the wrinkles before tacking them down to the surface.
We can see here the aluminium foil being worked around some access panels.
2.2. Curved areas
Curved areas shall be started from the middle. Since you are going to work the foil dimensionally to get rid of the wrinkles, you don’t want to exceed the material deformation capability and tear it. Working the patch from the middle will minimize this risk
Large curved areas can be very tricky to handle. In some cases it could be interesting to remove the foil backing on only one half and proceed with one half after the other.
Curved areas need practice. Each patch will be different and will require a different burnishing motion and strategy. You have to study the area first and decide how you are going to work it out. Do not hesitate to remove the patch if the covering goes wrong. It took me one day of trial and error to achieve proper results.
The key point to avoid wrinkles in a curved area is to put a bit of tension on the foil while tacking it down. You’ll have to “massage” the aluminium just before it sticks to the surface. Too much tension will almost certainly tear the foil apart. This is why the paper fiber smudging tool is so much useful here since the tip it is soft and flexible. Note that a used buffed tip will work better.
The canopy frame is usually a difficult area for applying Flite Metal.
I used a steel hole puncher to mark the rivet heads into the soft aluminium covering. It is a very easy and quick process. Since I didn’t completely seal the rivets holes during the preparation I was still able to locate and punch them in quickly.
I used several different puncher sizes to match the different rivets sizes of the real plane. I also made a special tool with a modified Philips screwdriver tip and a brass tube to engrave the panel screws.
When using the punching tool you should have a light hand otherwise the soft aluminium will make a ridge outside of the rivet print due to a possible excessive pressure.
4. Weathering technique
Flite metal weathering is a bit more time consuming than paint weathering. It requires different steps as explained below in the proper order.
4.1. Pre covering
The process starts before covering the plane as a first sanding of the aluminium patch is required, as explained before.
4.2. Creating the metal appearance
Working the aluminum will remove the initial dark dull gray color and make it shine. It will also create the typical bear aluminium wear appearance.
After having tacked the patch to the surface, I proceed with the following sanding operation: I use different 3M sanding pads and sponge grades or steel wool grades. The idea is to use a different grade for each panel. This will make every panel look slightly different from the other one. You will have to work the aluminium by crossing each pass. The last pass should be parallel to the air flow to achieve a realistic wear pattern.
4.3. Weathering the plane
After the later operation and the painting is done I start the weathering process. I use black and dark brown artist oil paint. I mix them with a bit of linen oil to obtain the required thickness. I apply the mixture only along the panel and rivets lines. I work perpendicular to the lines to put a maximum of paint in them. I then let it cure for a while ( from a few hours to a few days depending on the temperature, type of paint and required thickness ). I wipe it off with fabric tissues and a bit of mineral spirit. The stain will stay in the rivets, panel lines and along the raised panels ridges if you don’t use too much mineral spirit.
The artist oil medium applied to the panel and rivets lines.
4.4. Diversifying the metal shades.
The F-84G is made of different qualities of aluminium, especially on the wings and front fuselage. This gives a remarkable look which has to be reproduced.
I use the following technique:
I prepare different artist oil mixtures with the following colors: black, dark blue and brown. I dilute the colors with only mineral spirits so that it has the consistency of milk.
I then apply a different color to each panel with a cotton tissue according to the pictures of the real plane I have. The coat shall be very light and transparent. I let it dry completely ( about one hour ) and then sand it off with a 3M green sanding sponge. The required effect will be done by varying the sanding intensity and pattern.
The wing after weathering and dirtying.
4.5. Making airflow streak marks
Long airflow marks are done with aquarelle paint and a lot of water. I simply put some paint on the wing leading edge or surface front and wipe it with a wet cloth along the airflow motion.
Diffused panel marks are done with artist dry chalks. I place a tape on the front panel line side a apply the chalk with the same paper fiber pen that I use for Flite Metal.
I did this step after painting and applying the nomenclature and other dry transfer marking.
If you want to seal everything, you’ll have to apply a thin clear coat as a last operation.
The wing shown after weathering. Note the different aluminium shades and heavy dirt marks on the flaps behind the wheels.
The airflow streaks on the upper surface are more subtle. No heavy dirt here but a combination of rain and airflow marks.
5. An example of Flite Metal works
Here are a few pictures of the F-84G I built 4 years ago.
The "Four Queens" at dusk with all the lights on.
Some closer details of the panel works and markings.
Detailed view of the cockpit area.
The panels and markings at the rear of the canopy.
The nose gear section details.
A view of the left wing.
The "Four Queens" ready for another mission.
The following is a step by step tutorial on applying Flite-Metal.
An easy way to remove the metal from the roll without wrinkling.
Sand surface with 320 grit
Hold against flat surface while releasing to avoid curl.
Burnish/press onto surface.
Lay masking tape right up to edge of panel.
Overlap next piece onto tape.
Use ruler and #11 blade to cut, but leave tiny lap.
Burnish edge down.
Sand lap edge to remove overlap.
Now you have level butted edge.
Sand overall with 320 grit.
Use straight edge and #2 mechanical pencil to impress panel line.
Use different gauge needle/tube for rivet impression.
Here is the result after having imprinted rivets on the access panel.
A specific ruler is used to imprint panel shapes with a #2/ 0.5 mm paper pen.
After all panels and lines are printed, sand again with 400 grit in a single direction, no circular sanding.
Use Wizard's Metal Polish on some panels.
On that example, the center panel is masked to keep it at a different grit grade.
Here is the result after buffing off the dry paste and removing the tape.
Note that the sanding and buffing paste remains start to naturally weather the panel edges.
These are the basic steps. The only requirement from you is to now sand/cut/tape till your fingers bleed.
Here Here are a couple of old pictures from my TOP GUN jets.
Enjoy, and thanks for looking.
We are proud to introduce a new innovative type of product to the market.
These are aero grade structural carbon fiber and basalt fiber sheets.
I designed these sheets specifically for jet modelers.
The very specific thing about this product is that it is designed for both structural reinforcement and to improve the look of the internal structure. As such it features one face with a nice satin look and one face with a ready to remove peel ply fabric.
The peeled side will ensure the absolute best bounding characteristics onto any type of material used in a jet and is totally free from any release agent. So it is just a matter of cutting your plate, removing the peel ply and gluing it with any type of epoxy in your plane.
Up to now, carbon fiber plates were having two shiny faces produced in a hydraulic press with release agents. This type of product would require careful prepping to ensure maximum bounding with in a three stage sequence.
.The first stage implied the removal of the release agent with a chemical. This in itself could be a problem as very few manufacturers publish the type of release agents used. There are different types on the market that need to be removed either with warm soapy water, white vinegar, or acetone .In the case where the release agent was not known, all three methods had to be used. .The second stage was about scuffing the face to be glued to ensure a proper bounding surface. This would be done with a coarse grit carbide rotating tool at fairly low speed to avoid heat soaking and could have taken a long time if the surface was large. .The first stage required to remove any dust from the gluing area via a careful vacuuming then washing. drying was required after washing and would also increase the prepping time.
All these step were taking a very long time and keeping the sequence was necessary . Skipping the first step for example exposed you to the risk of embedding the release agent into the carbon structure while sanding it down, reducing the future bounding effect. Similarly skipping the third stage would make you glue your plate on a layer of carbon dust.
For all these reasons I found out that laying up the plates with a peel ply on one side would be extremely valuable for the user. The added benefit of leaving the peel ply in place is: protection of the carbon fiber surface, and ease of cutting. We recommend cutting the plate from the peel ply side with a hack saw fitted with a ceramic cutting blade ( the ones that have a diamond coating ). This will ensure that the satin face is not scratched. The peel ply being still in position during the cutting process will help the hack saw socket to glide on the plate. Additionally, the plates feature a very unique construction. The outer plies on both satin and peel side are laid up from high quality waving fabric with a perfect visual aspect, without any air bubbles. The core of the plate is layed up from a very specific fabric called quadriaxial. This fabric is waved at 90 degrees and 45 degrees at the same time, ensuring optimal rigidity in 4 directions, hence its name. This ensures a very high structural characteristics in 4 directions and gives an almost uniform stiffness to the plate.
The other very specific feature of these plates is the type of impregnation. I tried different type of techniques for my plates for several years: wet layup, pre-preg and infusion.
.Wet layup tends to get the fabric over-sutured by the resin and not optimally resistant. Good visual aspect without any air bubble requires to use a hydraulic press at extremely high pressure. In practice, air bubbles are always present. .Prepreg is better but also requires a very strong hydraulic press to chase all the entrapped air out of the satin surface. .The best process I found was to infuse the plates with specific resins. The fabrics are layed up dry on the marble and the resin is sucked by vaccum, chasing absolutely all the air bubbles. The fabric is also optimally impregnated with this method with no resin excess.
Finally, the plates are post cured at 60 c/ 140 F and have a plastic point of 80 c/ 175 F, and will keep their strength even in the hottest summer conditions.
We use similar structural plates on all our professional multi copters and for UAV applications with 100% success. The plates will be available in 1,5 mm/ 0,06" and 2 mm/ 0.08" thickness for the time being. Sizes will be 10" by 20" and 20" by 20" initially.
There is mostly one source of heat in remote control jet: the turbine.
Two types of heat will be found: readiating heat and direct exposure to the jet efflux.
The first one will generate moderate levels of heat, rarely above 100c/ 220F.
The second one could expose the equipment to temperatures up to 700c/ 1300F.
Although it can be relatively easy to hide the loom from hot areas due to radiating heat, it is much more difficult to protect it from jet efflux.
Radiating heat protection is just a matter of routing the loom appropriately and choosing the right cables. We recommend using high temperature silicon insulated heavy duty servo cables or PTFE insulated electrical cables.
However the second scenario would occur mostly in case of a catastrophic failure of the exhaust pipe. In this case the failure would be certainly recognized in flight by the pilot and should lead to a turbine shutdown. So it is reasonable to ensure protection to high temperatures for 3 to 5 seconds.
i have conducted a series of test on some MIL spec and aero grade cables and cable sleeves to understand a bit more how the equipment would hold in this case.
Here is a flame test conducted with the HD high temperature silicon servo cable. The cable is directly exposed to a 1000c propane torch flame:
Silicon servo wire flame test from Oli Ni on Vimeo.
The cable hold the flame for 3 seconds and the insulation integrity is still ensured, meaning that the conductive cores have not short cut.
Here is a test of the MIL spec cable in the same condition:
MIL spec cable flame test from Oli Ni on Vimeo.
The same result is found after a 3 seconds exposure at 1000c. The insulation has not melted.
Now let's see what happens to a regular high quality servo wire ( 20 AWG, PVC insulation ).
PVC insulated servo wire flame test from Oli Ni on Vimeo.
During the exposure, the bright glow shows that the insulation is burning. After 3 seconds, the insulation is totally melted and the copper cores have fused. The loom has completely short cut.
In general the high temperature cables would hold a jet efflux of 700c ( full thrust ) for about 30 seconds before melting the insulation and short cutting the cores. A standard PVC cable would not hold more than a few seconds.
So the idea would be to protect the system by using these cables anywhere downstream the engine. In case of catastrophic failure of the thrust pipe, there would be enough time to recognize the problem and cut the engine while maintaining the integrity of the electrical system.
However, standard PVC cables could still be used in this area by protecting them with flame resistant cable sleeves. Here is a test made with our high temperature kevlar sleeve:
The same PVC cable as before is now inserted in our kevlar sleeve and exposed to the propane torch for 5 seconds. The cable barely shows signs of overheat and the sleeve, although black, is still in one piece.
Kevlar fiber cable hose flame test. from Oli Ni on Vimeo.
This type of protection is completely possible and would ensure the same level of protection as using high temperature cables on standard looms.
Now the next level is to use our high temperature cables in heat protection sleeves. In this case, the loom would be able to sustain jet efflux for minutes, probably longer than what an airframe could take, even protected with ceramic blanket...
Here is a new article on how to cut a perfect hole in glass carbon and kevlar laminates.
The basics is very simple: use the right tool at the right speed.
The tool is by far the most important part of the equation. I use fantastic diamond coated carbide brad point jobbers specifically designed for this job. They are high quality aerospace drill bits made in the U.S.A.The jobbers are carbide hard diamond coated and brad point shaped
to penetrate the toughest carbon fiber and kevlar fiber laminates. The
flute shape enables an easy extraction of the drilling material up and
out of the hole, reducing burring. This makes very clean holes even in
softer glass fiber and kevlar laminates. They stay centered without having to make a hole point.
The second point of the equation is to use the proper drilling speed: I recommend 500 RPM maximum with these bits. Any faster and the laminate is going to heat soak. This is very detrimental to the drilling process as the material will soften and get sticky ( resin reaching its plastic point ). Then the precision of the hole will be ruined as soft fibers get stuck between the flute and the hole walls.
Similarly, it is important to allow the material to stay cold on laminates thicker than 3 mm. I typically recommend to stop the drilling process every 3 mm depth and check for temperature. Usually heat soaking starts at about this depth.
It is important to vacuum the part for any drilling deeper than 3 mm to ensure that the de-burring zone stays unobstructed. This improves the deburring process and also avoids heat soaking.
You will want to use a slightly softer material behind the part to even out the drilling pressure and ensure a soft exit transition of the jobber at the other side of the part. This is very important to ensure that both surfaces of the part are free of any chipping after the drilling process.
Also DO NOT use any lubricant. Dry drilling is important on laminates as lubricant would certainly chemically interact with the matrice of the material and soften the fibers of the laminates. This would also reduce the de-burring process.
Here is a video of a hole drilling in a very hard 3 mm prepreg aero grade carbon part:
Hole cutting in 3 mm carbon laminate with a column drill. from Oli Ni on Vimeo.
Note the hard wood block below the part and the slow rotation speed ( 500 RPM ). The part being 3 mm thick, not vacuuming is necessary.
And here is a video of the same hole drilling in the same 3 mm prepreg aero grade carbon part but this time using a hand drill:
Hole cutting in 3 mm carbon laminate with a hand drill. from Oli Ni on Vimeo.
As you can see, the process is as easy, clean and fast as with the column drill.
Using a cutting mat below the part to drill is important to avoid surface chipping on the other side of the part. There is no need to vacuum the part neither in that case. The hole cut is super clean as you can see.
I will add a video of the same process with a kevlar laminate when I have one in hand. With kevlar, I tend to drill a bit slower and avoid applying too much pressure to the part. Low pressure is important to ensure a clean cut of the fibers and thus a clean hole.
Note that I do not recommend the use of carbide rotary grinders with kevlar laminate. These only just mess up a hole by freeing up fiber strands without cutting them. The only way to cut clean holes with kevlar is to use these drill bits.
If you need to cut a conical recess for countersink screws, we have some top-of-the-line 6 flute carbide cutters:
They come in two two sizes.
The small size has a 1/4" flute is particularly adapted to super scale embedding of micro countersunk screws.
I also use it to machine offset hinges securing screw recess, and for scale panel access fasteners.
The other size is 1/2" flute and is very handy for bigger countersunk
screws like nylon screws, retract fasteners that need to be flush, or
any other heavier duty job.
Both tools are USA designed and made titanium oxide coated carbide cutters.
Here is a video showing the use of the 1/4" flute countersink on the Scorpion Mk2 fuselage:
Cutting a countersink recess in composite laminate. from Oli Ni on Vimeo.
With 6 flute bits, you need to be careful about the rotation speed. Too fast and the flute will vibrate and the hole will have ridges. A slow speed is recommended on these cutters.
Behotec is now offering a new line of electric retacts
This line is based on the world renowned pneumatic gears and is updated with a few interesting upgrades as you will see later.
The full range of Behotec gear is now
available as the e-Tract version, and I have ordered the Scorpion Mk2 version
to compare it with the same pneumatic set.
In the following lines I will show you the new electric set side by
side with the pneumatic one.
First of all the modifications:
1. Obviously, the pneumatic actuator has been swapped with
an electric motor, driving a screw jack.
Here is the pneumatic version:
and here the electric version:
2. The trunion shape has been slightly altered to cater for
the bigger diameter of the screw compared to the pneumatic pushrod.
3. The screw goes all the way to the retract wall and is
therefore very rigid, enabling a very precise position of the trunion. This is
important due to the next feature.
4. The motors used are stepped motors. This means that the
control unit has got a position feedback of the trunion, enabling a very
precise positioning in the stops. The fact that the screw is rigidly fixed on both sides helps in achieving a very high precision in the steps resolution. A typical travel on the C36 model is 7600 steps.
5. On the Scorpion set, the struts are square instead of
round. This gives a little bit more drag on the gear, which is welcome on this
model, as well as a better lateral rigidity.
The gear overall looks very nice and high tech:
The pneumatic version:
vs the electric version:
The weight difference on this gear is 100 grs/ 3.5 oz
The complete e-Tract gear without battery is 1125 grs/ 40 oz
whereas the the pneumatic version with the valves is 1025 grs/ 36.5 oz.
6. The gear Control Unit is very advanced.
It features the following inputs:
Battery ( 2S, 3S Lipo and 2S, 3S A123 accepted )
RC rudder, RC brake, RC gear
and the following output:
brake 1, brake 2,
mot 1, mot 2, mot 3.
The controller menu is also very advanced and can be
accessed through the optional ProJet GCU ( the same used for Behotec and
It features the following screens on the main menu::
Reason for stop on the 3 gears.
On the picture below, gear 1 and 3 have stopped into their final step position, gear 2 due to timeout.
The status of the control signal:
The actual current consumption and battery voltage:
The step count for each motor ( ie position of the trunion
The gear, brake and rudder signal position in %:
The setup menu ( called master mode ) gives you the
possibility to change the following:
Max motoring time
Max current before tripoff
Travel steps for the trunion
Brake stops and anti lock setup.
Finally every gear is setup and tested at the factory before
You just need to plug it in and verify that no friction will
occur on the airframe during travel.
Here is a video of the gear system setup in my Scorpion Mk2:
New Behotec e-Tract gear. from Oli Ni on Vimeo.
The retract travel is programmed with a start step and end step.
resolution Behotec is working at on the C36 is
35mm/7600= 0,0046 mm per step or 4,6 thousands of a mm. Thanks to the very
accurate trunion machining, the position can be acquired very
precisely. This is working extremely
well and the positioning of the trunion assembly is very
consistent and extremely stable.
The electronics has a current tripoff and timeout function as an additional safety feature. The main stop function is the step position.
In practice the gear always stops at the stop step ( positioning stop )
and not from current tripoff with the trunion right into the end of the groove. The menu on the GSU allows to see that.
All together, this upgrade is offered at a price increase of 40%. I think that it is quite fair considering the setup ease, everyday dependability, the quality of the electronics and control system and the software ergonomics.
Hysol glue is a great product. The cartridge system enables you to meter exactly the proper mix ratio and the tips will get you to do a professional job very easily.
However, there are basically 3 choices of glue.
1. Hysol 9462
It is a great glue that makes very strong joints and remains slightly flexible when cured. This is perfect for gluing formers in a fuselage for example. This glue is slightly more expensive than the two other types and has a setting time of 7 hours, which is quite long and requires building planning to avoid wasting time.
It has the highest shear strength of all 3 types of glues.
2. Hysol E-20NS
This is the glue I use the most. It is very thick and never sags. It is completely white, sets quite fast and becomes very hard when cured. Fantastic product.
3. Hysol E-20HP
This is a useful type of glue as well. I use it when I need to push the glue in thin space/ holes/ cracks as it is quite fluid. This is the perfect glue for fixing hinges, repairs, retract plates reinforcing, etc...
The glue sets in about 20 minutes and is translucent. It sets very hard and has a slightly higher shear strength than E-20NS.
Note that some people have reported strong skin allergy with E-20HP.
In practice it is absolutely imperative to use proper Nitril/ Ultra nitril gloves when working with these products. One can find very nice thin Nitril gloves on the market that would not reduce your skin feel too much and protect you nicely for a certain period of time as indicated by the manufacturer. I also recommend the use of a mask with organic fumes filter when using epoxy as the vapors are quite toxic.
I am getting a lot of questions from customers about cartridge tips. "Should I use one?" "isn't it better to mix the glue all by myself?"
I have been using Hysol glue for many year in professional/ aerospace applications and the answer is simple: I am using long, short and no tips!
Here is how I use a tip for my application.
1. If I have to glue large surfaces together or blocks, I use no tips and mix the glue directly on a post-it block. When I have finished the job, I peel off the used sheet and the block is ready for the next mix!
This technique is fast and saves glue as there is no unused mix left as in using a tip.
2. If I need to dispense the glue precisely in a spot or if I need to make a long thin glue line like along a former, I use a short tip. The short tips we use are making a perfect mix and the result is excellent. They waste less glue than the long tips and are easier to clean.
3. If I need to dispense glue in a far location, then I use long tips. In that case I am ready to sacrifice some material for accessibility.
In practice for all the epoxy gluing job I use no tips in 30% of the cases, short tips in 60% of the cases and long tips in the remaining 10 %
The tips we sell are the green square types. After having used all types, I found these ones the most suitable for us. They are easy to clean and can be re-used many times if you wish to. Here is how to clean them.
Immediately after having used a tip, remove the green mixing insert from the body by pulling it gently with a pair of thin nose pliers.
Dip the green insert into acetone and brush it with an old firm toothbrush. Remove the glue mix from all 4 faces of the insert
Clean the empty body with cotton ear buds in the same acetone bath. Use the ear bud as a piston in the body.
You might need to change the acetone bath and re-clean both the insert and body to ensure that no remains of glue+acetone are left in the corners.
When everything is clean, let dry overnight before re-assembling the tip. This step is very important or you might end up with a locked insert...
I have been able to re-use tips about 10 times with this technique.
Some people might tell you that short tips do not mix glue properly. I have been using the tips we sell for over 10 years and never got any improperly mixed product. I believe that inconsistent results come from cheap Chinese mixing tips and guns, or from the Hysol 9462 air bubbles problems described in our Bulletin 1 as seen in the download section of this page:
We have come across a number of non branded mixing tips coming from China that were improperly manufactured, with wrong grid pattern or large grid clearance creating product slippage outside of the mixing grid. This almost systematically resulted in improper glue mixing and poor gluing results.
Additionally we discovered that cheap Chinese glue guns were a lot more flexible than the genuine Loctite guns and allowed the pistons to push asymmetrically in the glue gun. This would also result in an improperly mixed product.
We strongly advise our customers to use genuine products to avoid safety hazard induced by improperly mixed Hysol glue.