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ESLT 1.5 Build Guide


The first ESLT was built almost two years ago, and a lot has changed since the original. This is the latest version MHA is producing, and the design will continue to evolve from here. A 3D printer is required to make these blasters unless you are clever enough to substitute all the printed pieces with something else. It's definitely achievable, but the 3D printed version is obviously a lot easier to build if you have the necessary tools. There are no physical pictures of the assembly process or the machining process, but instead pretty drawings I did in Inventor that are both better and worse than doing regular pictures. One thing I really hate about most writeups people do is the wall of pictures that are either terrible quality, millions of them, or both. 

Like the first writeup, this is more of a "Build Guide", or a general reference to building one of these. If you're looking for step-by-step instructions, you're building the wrong blaster. However, if some things don't make sense or aren't clear, please complain about it.

Printed Part Files

As a person involved with 3D printing, I always rage hard when people don't post a file that you can actually edit. Most people will post some stl's which are garbage if you have to modify even the slightest thing. In response to that, I'm hosting both .stp files and .stl files so if you have some modeling software that can import stp's, then you can actually edit parts if you have to. 

To download .stp files, right click the link and select "Save Link As" and name the file with the extension ".stp".

MainHandleZPrint (Vertically Printed)
STL    STP Format
MainHandleSide1 (Two Halves)
STL    STP Format
STL    STP Format

STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
PumpGripSpacer (x2)
STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
STL    STP Format
StockFlange (optional)
STL    STP Format

And of course, a stp file of the entire ESLT 1.5 assembly.
STP Format

McMaster List

Part McMaster # Length
CatchSpringRod.8646K31 8646K31 1.50''
PlungerRod.8974K31 8974K31 12.00''
ORingTube.8565K36 8565K36 0.75''
AluminumBarrel.1658T11 1658T11 10.00''
SpringPost.8576K15 8576K15 3.00''
9657K82.CompressionSpring 9657K82 2.00''
90273A151.FlatHead6-32x3-4 90273A151
90273A153.FlatHead6-32x1 90273A153
90272A151.6-32x3-4 90272A151
EyeBolt1024.9686T73 9686T73
Nut1024.9686T73 9686T73
Nut0250.94812A700 94812A700
ORing.PlungerSeal.9452K36 9452K36
ORing.RodSeal.9452K171 9452K171
ORingSpacer.94639A139 94639A139
RubberCushion.9452K206 9452K206
90272A145.6-32x5-16 90272A145
4880K636.PVCWye 4880K636
90272A153.6-32x1 90272A153
4880K977.PumpGrip 4880K977
90272A150.6-32x5-8 90272A150
92311A146.SetScrew6-32x3-8 92311A146
90126A007.6-32Washers 90126A007
9432K125.ExtensionSpring 9432K125
4880K44.1.25Tee 4880K44
0.5PVCClip.49035K83 49035K83 12"
0.5PVCEndCap.4880K51 4880K51

Optional Add-on Stock

1       StockFlange001

1 StockPlate.8619K431 8619K431
1 StockPad.8647K29 8647K29
4 90272A148.6-32x1-2 90272A148

Hardware Store List

QTY Length
1 1.50InchPVCClamp 9.00''
1 0.50InchCPVCStubRedirect 1.00''
1 0.50InchCPVCElbow
1 0.50InchCPVC.PVCBarrel 4.00''
1 0.50InchCPVCStubWye 2.00''
1 1.25InchPlungerTube 8.00''
1 1.25InchFrontTube 17.00''
1 1InchPVCPrimingTube 8.00''
1 1InchPVCPumpGrip 4.00''
1 1.25PVCPumpGripTube 3.00''
3 0.5PVCStub 3.50''
1 0.5CPVCCoupler

Essential Tools
-3D Printer w/ no less than 7x7x7" print area
-Scrollsaw or Hacksaw
-Drill press and/or power drill
-Dremel w/ cutting wheel or Mill/Scrollsaw
-7/64”, 5/32", .260" (or slightly over .250), 1/2", 5/8" drill bits
-#6-32 tapping bit
-#10-24 tapping bit
-1/4-20 tap and die set
-5/16-18 tapping bit
-Scissors and/or file
-Countersink (Any size, really)
-Hot glue and/or super glue
-Duct tape
-Silicone lube
-Safety glasses
-Vise and/or wrench
-Tape measure, ruler

Very helpful, not critical:
-Tube holding jigs
-Hole marking jigs
-Chimo Cheese
-Belt Sander (stock)

Printing your Components

MainHandleZPrint - 0.6mm nozzle, 5 perimeters, 30% infill - This is the part of the handle you physically hold and is the biggest print on the blaster. There are two ways to do this. You can do it vertically, like I have here, or you can do two halves and glue them together. If people don't have printers that can print up to 160mm in the Z axis, you'll need to do them in halves. If you have a finer nozzle (less than 0.5), you should also do them in halves. Layer adhesion is the weakest point on parts that come off these printers, so extra/thicker perimeters are a must if printing vertically. Post-print you'll have to tap the two holes (#6) at the top of the print where it attaches to the HandleClamp. You also may need to drill out the three holes (#6 clearance), where it attaches to the FrontHandlePiece.

FrontHandlePiece - 0.6 nozzle, 3 perimeters, 30% infill - This is probably the most challenging print on the blaster. They are pretty long (175mm) and will warp at least a little bit unless you really have your settings on your printer super fine tuned. I've found adding lots of brim helps, especially adding brim to your model so the brim is actually attached to the printed part for a layer or two. Post-print you'll need to tap the two holes (#6) where it attaches to the HandleClamp. You also may want to drill out the two holes (#6 clearance), where the CatchPiece and Trigger are mounted.

CatchPiece; CatchInterface - 0.6mm nozzle, 3 perimeters, 100% infill - The CatchPiece is basically the catch of the blaster (hence the name), where the CatchInterface is more like the "catch notch" in a normal blaster. These two pieces need to be 100% infill since they see a lot of wear during use. Having a larger nozzle isn't critical, but it does make for faster printing. Post-print you'll need to tap (1/4) the only hole on this piece.

Trigger3DPrint/Mirror - 0.6 nozzle, 3 perimeters, 30% infill - These don't really don't matter how they're printed. You'll need to glue the two piece together after they are printed. After they're glued together, drill out the hole (#6 clearance).

ReDirectPiece - 0.6 nozzle, 3 perimeters, 100% infill - We recently started making these solid because of some people having problems with them breaking in particular blasters. It didn't happen a lot, but it's better to be safe when it comes to this piece. It's centrally located in the blaster, making replacement pretty difficult without taking the whole blaster apart. After it's printed, drill out the holes for the CPVC stub, and the Rod Seal with a 5/8" drill bit. You want this piece to be somewhat loose in your Plunger tube. Hammering/tight fits are not good when it comes to this piece.

PumpGripSpacer(x2) - 0.35 nozzle, 1-2 perimeter, 100% infill - These are very thin, tall pieces, that benefit from having a smaller nozzle. They have to be large enough to fit inside the 1.5" Reducing Tee, but small enough on the inside diameter, to pass over the 1 1/4" PVC. 

EyeboltAdapter - 0.6mm nozzle, 3 perimeter, 100% infill - The Eyebolt Adpater needs to be strong and is a quick print with a larger nozzle. Post-print, you'll have to tap one end with a #10-24 tap, and the other end with a 1/4-20 tap.

BarrelSpacer - 0.6mm nozzle, 4 perimeters, 30% infill - These don't really need to be this large, but we like the look and how it holds the barrel very tight. 

ESLTPlungerHead (Front/Rear) - 0.6mm nozzle, 3 perimeters, 100% infill - More information on these can be found here. You'll need to tap both holes for the plunger rod, post-print.

WyeSpacer - 0.6mm nozzle, 3 perimeters, 30% infill - Also another print that doesn't have to meet any specifications. This print simply gives you a wedge in between the wye and the front tube to tape the barrel assembly from wobbling.

StockFlange (optional) - 0.6mm nozzle, 3 perimeters, 30% infill - If you have a printer you might as well do this piece. It attaches the plunger tube to an HDPE sheet which is hot glued to a piece of foam, for comfort. This is a highly recommended add.

Tube & Rod Machining

The Priming tube is the linkage from the PumpGrip that pushes on the CatchInterface, which pushes back the plunger rod. The top slot doesn't need to exist, but it's easier to do on a scrollsaw like that. You can also Dremel or mill it, but you only need the bottom slot. The holes should be 7/64" or a #6 pilot, and need to be tapped afterwards. These need to be fairly centered holes so the 1" is mounted centrally inside the 1 1/4" front tube.

Make sure your PVC is smooth on the inside. The majority of PVC we encounter is very bumpy and awful on the inside, creating unnecessary friction and a shitty seal. Fitting your Redirect piece to this can be kind of tricky but you want to make sure it's a loose-ish fit in the tube. More information on that assembly will be explained later. The holes are easier to drill after you've inserted and attached your ReDirectPiece unless you have super tooling (you don't), so don't drill these yet.
The biggest tube to machine, and requires some pretty long slots. We do these on a mill, but a scrollsaw is probably the next best option, followed by a Dremel, which is pretty terrible. The slot should be at least 3/8" wide, if they are centered. If they're off, they'll like need to be oversized.  The holes should also be #6 pilot holes and drilled after you've assembled some stuff. Again, this will be explained more later. The larger hole in the front is 1/2" in diameter which holds the spring post. You'll also need a slot on the bottom for the CatchPiece to clear, which should be around 1/2" wide.
These are basically a tube cut almost in half, leaving one side to be a little more than a half tube. This will clamp over/slide over your 1 1/4" tubes, and connect your handle to them. It needs a 1/2" slot in the bottom, with 5/32" or #6 clearance holes to attach to the handle. They also need to be countersunk. The holes near the top of the clamp should be #6 clearance holes, and you should drill them before cutting the tube in half.

Pretty straightforward here, make sure you chamfer the CPVC/PVC barrel combo to allow a smooth feed for the the darts. Instead of using a CPVC coupler, you can also use a length of 1/2" PVC drilled out to 5/8". Make sure you super glue your CPVC/PVC barrel combo because you don't want that coming un-done.
This can be a difficult piece to machine. Cutting it to length is pretty easy, but making the threads will be difficult unless you have special tooling. We're probably going to sell a plunger rod machining kit, with the necessary printed parts to make this a much easier process. More on this later.

If you don't want the super tooling, you'll have to cut the aluminum rod to 11.5", and use a die to cut threads 1.5" long on both sides. During this process you'll have to figure out a way to vise the rod without damaging it, and when you're actually turning the die to cut the threads, you have to make sure you're not bending the rod. Both of these will cause major issues later, mostly the plunger rod having tons of unnecessary friction.

These are just small bits that you'll need later on. The holes on the 1 1/4", 1" Pumpgrip tubes, you'll drill these later. The hole for the spring post should be 5/32" diameter, and roughly .25" away from the top.

Super glue the CPVC/PVC wye stub. You need this to stay together when you press fit the Barrel Assembly together.

Handle Assembly

Now onto the major assemblies. Most important and easiest, is the Handle Assembly. It's pretty straightforward from the drawing here, and everything should go together nicely. Your spring length should be roughly the same as the Catch Spring Rod.

Front Tube Assembly

This can all be left un-assembled until later. It's really just here for a reference. 

PumpGrip Assembly

This assembly must be done inside the 1 1/4" Front Tube. You'll need to drill holes in the side of the PVC Reducing tee, that line line up with the PumpGripSpacers. There is no easy way to get these holes lined up without special tooling, but you can just drill them a bit oversized so the screws will pass through. These two sets of holes, and the holes in 1" Priming tube should all line up, and you'll secure it with the #6-32 x 5/8" long screws.

For the bottom grip portion of the Reducing tee, nest your stub of 1" PVC inside your stub of 1 1/4". You'll need about 1-2 duct tape rings for it to stay centered and not wobble. Drill one 7/64" hole straight through the Reducing tee and 1", and then below it another hole through the 1 1/4" and 1". Tap these two holes (#6) and put in the two set screws, making them flush with the grip. 

Barrel Assembly

This is self-explanatory as well. It's not necessary to glue any of these pieces together.

Plunger Rod Assembly

When you assemble the Plunger Rod, only do the back side of it first, containing the plunger head. The rod seal and ReDirect Piece need to go in between this assembly. 

Plunger Tube Assembly

This is the step where you'll need your hot glue gun. Your ReDirectPiece should be loose in the Plunger tube, so add a small line of hot glue around where it's being inserted into the tube. Push that in all the way until the Plunger tube butts up against the top of the ReDirectPiece. 

The nylon spacers should be super glued inside the polyester tubing, with the o-ring in between, obviously. This is your rod seal. You don't need to glue the rod seal inside the ReDirectPiece. This should be a nice press fit. Same goes for the CPVC stub, but if it doesn't seal, use a little hot glue here as well.

During the Final Assembly, you'll drill the holes you need to secure this assembly to the rest of the blaster. Right now, you should have no holes in the ReDirectPiece, or the Plunger tube.

Stock Assembly

The shape of the foam piece and stock plate are really up to the user's preference. Make sure you drill speed holes after you've put the stock on the plunger tube. Your blaster won't work otherwise. Just use the 5/32" bit and drill 3-4 holes through the side of the flange and the plunger tube to allow air to pass through when firing.

Final Blaster Assembly

We're to the final assemblies, and now you'll be drilling all the holes I told you to wait on. First you'll want to attach your PumpGrip assembly to the Front Tube. Put the 1" Priming tube inside the Front Tube, followed by the Reducing Tee over it, and then slide in your PumpGripSpacers, lining up all the holes between the 1" Priming Tube, PumpGripSpacers, and Reducing Tee. Assembly with 5/8" long screws. Make sure the screws on the PumpGrip are facing towards the front of the blaster.

You can now drill out your 7/64" holes that are in the side of the Front Tube. Mark the holes by using the existing holes in the HandleClamp, making sure the slots (side and bottom), are lined up with the Handle Assembly. Tap these holes and secure with 1/4" screws. You can now put on the BarrelSpacer, but still leave off the Spring Post.

Before you put in your plunger rod, clamp on the Plunger Tube Assembly on the back of the HandleClamp, lining it up with the holes already drilled in the HandleClamp. Make sure your ReDirectPiece is pointed straight up, so the Barrel Assembly is all straight and square. The holes should be 3/8" from the edge of the plunger tube. Mark these holes in your Plunger tube, and drill through the Plunger tube and ReDirectPiece with a 7/64" bit. Tap and deburr the holes. 

Insert your plunger rod into the Plunger Tube Assembly, and attach the front end of the Plunger Rod Assembly that I told you you'll put on later. Make sure you lube up the Plunger tube and it doesn't hurt to also lube the rod seal.

Attach the Plunger tube assembly to the rest of the blaster using the holes you just drilled, and 3/4" long screws. The screws should stick out slightly past the ID of the ReDirectPiece, although you'll have no idea unless your blaster is clear.

I don't have this part modeled, but make sure you have your extension spring or latex tubing is already attached to the Eyebolt when putting this assembly in the rest of the blaster. You can now put in the Spring Post, through the barrel spacer, securing it with a 1" long screw. Obviously make sure the other loop of the extension spring goes through the Spring Post. There should be a small amount of pretension with the extension spring.

Now you can put on your stock of choice, secure it how you'd like, and add the Barrel Assembly. The aluminum barrel will clamp very tightly inside the barrel spacer. Make sure everything is lined up, add your WyeSpacer, and use duct tape to secure your Barrel Assembly, preventing the wye from moving side to side. If you'd like to make it more permanent, feel free, but I like to keep the Barrel Assembly still easily replaceable.