167 replies to this topic

[SpeedyNH]

that's a very interesting epoxy coating. i guess that you don't have to worry about overheating with short drag runs. 

-didn't they make 3-pole arms? 

 

(double-ought-ninety- there's some lightweight hardware!) 

[Alan Draht]

Acraglas epoxy was used on the Ram armature pictured.

 

Acraglas is made by Brownell and is designed as a non-shrinking, glass-hard, bedding material for rifle stocks and scopes to enhance accuracy.

 

Acraglas epoxy was used by pro slot car drag racers in the New York City area in the mid-1960's.

 

As a West Coast drag racer, Gene Husting says in his build articles that he used Klenk's epoxy on his armatures.  Klenk's doesn't make a suitable epoxy for this application anymore.

[Alan Draht]

I disassembled the Ram 857 6-volt motor and used 2-56 motor screws to temporarily attach the motor's field laminations and magnet assembly to the right side frame rail.

 

At this point it became clear from looking at the photos, and from holding the pieces in my hands, that the left side frame rail in the Maldonado dragster is held in position by the frame's cross braces, not by the 2-56 screws used to fasten the motor's structure to the right side rail.

 

This is a major difference between the Husting and Maldonado dragsters.

 

That, and the fact that the frame rails are straight and parallel to each other at the rear end of the car, then taper evenly on both sides to a 0.750" wide nose at the front...

 

...and it dawned on me that I need help assembling the car in the form of a jig.  

 

A jig will hold the frame rails in position while the frame's cross bracing is fabricated.

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[Alan Draht]

The dragster's Corian set-up board will need holes drilled accurately at key intervals for posts to align the frame with respect to the rear and front axles, drop arm and guide flag, etc.

 

This will be done on the mill table.  Before that can happen, the rotary table will have to be removed from the mill's X-Y  table.

 

Prior to removing the rotary table from the mill, it was used to machine the "hubcaps" off of a pair of vintage K&B Model-Rama slotted front dragster wheels, duplicating the front wheels of the original Maldonado dragster.

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[Alan Draht]

After removing the rotary table, a dragster set-up board was mounted to the mill table.

 

Using the motor and magnesium frame parts fabricated so far, a chassis jig was constructed with 0.1250" brass posts.

 

At the rear end of the chassis, a fixed width of 1.370" is maintained to form a squared-off "box" carrying the motor's  components and the rear axle.

 

Forwards of the front end of the motor, the magnesium frame rails taper from 1.370" to a 0.750" wide nose tip.  The front ends of the frame rails are drawn together with a 3/32" rod and a couple of shaft collars.  This is temporary.  Brass posts will installed later.

 

The jig provides a stable platform to measure and fabricate the frame's cross-braces and guide drop arm.

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[Alan Draht]

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[SpeedyNH]

is that a corian block?

[Alan Draht]

Yes, Corian.  

 

Brass posts have been added at the frame's middle section and front end.

 

The Maldonado chassis jig was removed from the mill table.  The mill was only used to accurately drill the jig's post holes.

 

The chassis frame is positioned squarely and securely in the jig.

 

 

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[Alan Draht]

The Husting dragster's main frame rails are bolted directly to the motor's end plates and run straight and parallel from back to front.

 

Gene Husting didn't use a jig to build his 1966 R&C dragster because a jig wasn't necessary.

 

The Manuel Maldonado dragster does not use the motor's original end plates to set the width between the main frame rails at the rear end of the chassis.  The chassis's main frame rails curve in from a width of 1.370" at the rear end to 0.750" at the nose.

 

A jig is indispensable to building the Maldonado dragster.  I'd be surprised if Manuel didn't use one to build this type of magwinder.

 

 

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[Alan Draht]

Cross-brace beginnings...

 

 

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[Alan Draht]

Milling the other side of the lower cross-brace...

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[Alan Draht]

Checking how the part fits in the frame.  Lower cross-brace in position...

 

 

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[Alan Draht]

The upper cross-brace is fabricated the same way as the lower piece.

 

Both are made from 0.1250" thick magnesium plate.  This plate thickness accommodates 2-56 size fasteners.

 

Of course, both cross-brace plates will be heavily machined to reduce weight.

 

Besides their structural bracing functions, the lower brace will be machined to provide a hinge pivot point at the front end for the dragster's guide flag drop-arm.

 

The upper cross-brace will be machined to provide a location to anchor the rear ends of the front drop axle's outrigger rods.

 

The upper cross-brace will also be used to locate two 0-80 brass hex head bolts to fasten the sheet aluminum body panel to the top of the dragster's frame.

 

Another magnesium or aluminum cross-brace is need at the front upper corner of the motor, where the side rails and body dip down.  The motor's threaded screw cannot be extended to meet and brace the left side rail at this location because it would be in conflict with the motor's upper brush and post.

 

This cross-brace is also needed to provide a location to fasten the body to the frame, replicating the appearance of Maldonado's dragster.

 

I don't know what Manuel has in his car there in terms of a cross-brace or part to provide these functions.  It's a mystery to me.

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[Alan Draht]

Holes for 00-90 bolts and washers are drilled into the top cross-brace panel.

 

Like all of the panels, holes are drilled at 90 degrees to the surface of the panel's edge.  The panels taper in back to front, matching the main frame rails.

 

This is the set-up used to drill 90 degree holes on angled surfaces.

 

A rotary table mounted to a tilting angle table allows one to set the correct angle of the  workpiece, using a right-angle square aligned with the mill's vertical headstock.

 

 

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[Alan Draht]

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[Alan Draht]

Another top cross-brace located in front of the motor was created, as well as a brace panel at the nose which incorporates an assembly for mounting and securing the front dropped axle.

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[Alan Draht]

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[Alan Draht]

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[Alan Draht]

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[Alan Draht]

The underside of this panel was machined to create space for the motor's top front corner and clearance for the motor's top brush assembly and wire inside of the left frame rail.

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[Alan Draht]

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[SpeedyNH]

nice work!  i can't wait to see the motor come together. 

[Alan Draht]

I think I've made it out of the woods in the building process for this magwinder.

 

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[Alan Draht]

The armature is perfectly aligned and spins freely.

 

 

 

 

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[Alan Draht]

Frame details...

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