Jump to content
This site uses cookies! Learn More

This site uses cookies!

You can find a list of those cookies here: mysite.com/cookies

By continuing to use this site, you agree to allow us to store cookies on your computer. :)

Endeavor

Sectioned and Channeled Pocher Alfa Spyder

Recommended Posts

Posted (edited)

Some members may recall my thread that described my attempt to modify a Pocher Alfa Spider (K73) so that it would more closely resemble the Touring bodied prototypes.  The thread was destroyed by the third party hosting site.  I moved on to other projects, including the Model Factory Hiro 159M build posted on this site.

 

I am taking a short break from the MFH project to take up on the Spider where I left off.  I will slowly post an updated version of the old thread.

 

I began by building a new set of wheels.  That's where I began again, so that is where this thread begins.

 

Below are the Pocher parts that make up the wheel rims.  The three plastic rings, two inner metal rings (one is on the top left), and two outer metal rings (one is on the top right) are stacked to create the rims.  A total of seven layers.

 

Each plastic ring supports one layer of 20 spokes, 60 spokes per wheel.  Each layer has a different set of spokes, as you can see in the photograph.  The photograph also shows one of the 12 screws required to hold the rings together, and one of the 60 "nipples" that hold the spokes to the plastic rings.

 

The spokes sometimes must be trimmed to fit.  The plastic rings require considerable work to make them fit together without gaps.  All screw holes must be enlarged a bit.

 

And when you are done, you discover that the rings are not concentric.

 

DSCN2638.jpg

 

 

Below are the parts that make up each wheel hub, a completed hub, and another look at the three types of spokes and the "nipples".  I neglected to include the locking bottom nut, but it is shown in a later photograph.

 

The plastic hub parts require a good deal of work to ensure that the slots that accept the spokes are open and clear.  They must be worked a bit to make certain they can be rotated easily on the shaft and they must be thinned out a bit to reduce the height of the stack to ensure that sufficient threads protrude from the bottom so the lock nut can be secured.

 

DSCN2632.jpg

 

 

DSCN2635.jpg

 

 

Below are the tools I used to build the wheels.  Not shown are a pin vise and a few drill bits.

 

The soldering iron is used to heat up the spoke nipples to soften the plastic so they can be inserted.  Sometimes this is necessary, sometimes not.  The wooden stick is used to hold the parts in place while heat is applied.

 

The screw driver with ball handle is used to press the nipples into place.  The nippers are used to trim the spokes when necessary.  Like all classic Pochers, inconsistent quality control means that assembling the same part in different locations may require different methods.  The purpose of the tweezers, toothpicks, and file is obvious.  The Tamiya tweezers are an extremely valuable tool.

 

DSCN2644.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites

I've also modified the assembly for the Alfa wheels. To start with, I made a tap for the 1/16" Whitworth screw threads by soldering a long Pocher screw into a piece of hex tube. By setting the tube on alternate flats it's possible to file 3 slots into the thread - good enough to tap plastic. I pre-assembled the wheel rims step by step, filing back the plastic parts to the level of the metal rings. When the assembled wheel is painted, it's difficult to see the joins, and the rim looks much more of a  single piece.

There's also a better orientation for spoking the middle row, if you don't have this let me know and I'll dig it out....

 

Share this post


Link to post
Share on other sites
Posted (edited)

 

Below is the assembled first (innermost) plastic ring in the jig supplied by Pocher.  All of the plastic rings in this kit are black plastic.  They were painted silver long ago.

 

You cannot see it in the photograph, but the outside metal ring has been screwed to the bottom of the plastic ring.

 

A "nipple" was slid onto each spoke, each spoke was inserted into the center hub, and the other end of the spoke and the nipple were placed on top of the slot.  The nipple was then forced down into the slot, holding the spoke in place.  If the plastic was too rigid and brittle, with the soldering gun, I applied heat to the inside end of the "nipple" while pressing down on the outside end of the "nipple" with the wooden stick to "melt it" into place.

 

It's easy to make a big mistake with the soldering iron but, with practice, you soon get a good "feel" for pressing the nipple and spoke into place with or without heat.

 

When all the spoke were installed and checked that each was positioned correctly, I applied CA to hold them a bit more securely in place.

 

DSCN2686.jpg

 

 

In the photograph below the metal ring that fits between the two plastic rings has been placed in position.  It will fit better when the second plastic ring has been installed.

 

DSCN2695.jpg

 

 

In the photograph below, the middle plastic ring and its 20 spokes have been installed.

 

I don't know why the center hub appears to be oxidized in these photos.

 

DSCN2661.jpg

 

 

Below you see that the third plastic ring, the metal ring between the second and third layers, and the final 20 spokes and "nipples" have been installed.

 

DSCN2673.jpg

 

 

Here is the finished wheel.  In the rear you can see what the center hubs actually look like.

 

The stains on the metal ring are the result of careless storage by a previous owner.  The two outer rings will be cleaned up when the wheels are painted.

 

DSCN2680.jpg

 

 

The back of the finished wheel, including the lock nut not shown earlier.

 

DSCN2710.jpg

 

 

The completed wheel with Model Motorcars tire installed.

 

Note the hole for the air valve.

 

The bottom section of each "nipple" is visible because the metal rings are larger than the plastic rings.  They also are not concentric. Pocher made them that way.

 

I have completed five wheels, two more to go.

 

DSCN2721.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites
Posted (edited)
On 5/11/2018 at 8:19 PM, Jo NZ said:

I've also modified the assembly for the Alfa wheels. To start with, I made a tap for the 1/16" Whitworth screw threads by soldering a long Pocher screw into a piece of hex tube. By setting the tube on alternate flats it's possible to file 3 slots into the thread - good enough to tap plastic. I pre-assembled the wheel rims step by step, filing back the plastic parts to the level of the metal rings. When the assembled wheel is painted, it's difficult to see the joins, and the rim looks much more of a  single piece.

There's also a better orientation for spoking the middle row, if you don't have this let me know and I'll dig it out....

 

That's a great upgrade.  I wish I had known a week ago.

 

Rather than follow Pocher's instructions, as you suggested, I did rotate the second ring 120 degrees and made the spoke pattern symmetrical.

 

Thanks for posting this.

 

I'll try filing back the plastic rings on the one wheel I have not started.

Edited by Endeavor

Share this post


Link to post
Share on other sites

Here's a pic of one of my wheels - see what you think. Incidentally the tyres are Pocher, matted down with about 20 minutes rubbing with a Scotchbrite pad.

 

IMG_2154a

 

Share this post


Link to post
Share on other sites
Posted (edited)

Thank you very much @Endeavor and @Jo NZ for sharing those tricks.

I've bought one year ago on eBay an old Alfa Monza, found into a stat of incredible disrepair.

Wheels partially assembled or not, spokes and nipples loosed or disconnected, and overall  assembled in a very bad way

Your tuto will help me to reassemble then correctly

Regards

 

Edited by CrazyCrank

Share this post


Link to post
Share on other sites

Ahhhhhh-Pocher classic activity again....:wub:

 

Two wonderful examples shown here by expert builders. Plenty of Pocher tips and wisdom will follow. Both are obviously past wheel-solving problems but I would just throw in that I epoxied the Pocher base jig to a small plank of 1/8 steel which stabilized it and was a big help. The soldering iron trick brought back the tremors and sweats.....but the results always worth it when the model stands on these gems.

 

David is doing a radical correction to the fantasy Spyder that Pocher created; I know this will be a far more accurate 8C - after buckets of Milliput and dozens of saw blades.

 

But David, why SEVEN wheels? Triple spares?

Share this post


Link to post
Share on other sites
Posted (edited)
On 5/11/2018 at 8:19 PM, Jo NZ said:

I've also modified the assembly for the Alfa wheels. ..... I pre-assembled the wheel rims step by step, filing back the plastic parts to the level of the metal rings. When the assembled wheel is painted, it's difficult to see the joins, and the rim looks much more of a  single piece.

 

 

I built a wheel following your suggestion...

 

The two outside plastic rings were screwed to the two metal rings that form the outside edges of the wheels.  Using the metal rings as a template, the plastic rings were sanded down with a Dremel so the inside diameters are now flush with inside diameters of the metal rings.

 

DSCN2737.jpg

 

 

This photograph shows the other side of the same parts.  The sanded black edge contrasts with the silver paint on the top side of the part.

 

DSCN2740.jpg

 

 

This photograph shows how I clamped the two inner metal rings to the center plastic ring to produce a template.  

 

All three rings were sanded down to size with a Dremel.

 

DSCN2734.jpg

 

 

Below you see the spokes installed in the first modified plastic ring.  Modifying the rings has no impact on the process of building the wheel.

 

DSCN2724.jpg

 

 

This photograph shows how the nipples of first layer of spokes now sit flush against the outside metal ring.  It is a substantial improvement.

 

DSCN2730.jpg

 

 

Thanks again for the suggestion.  The improvement is very apparent and important.

Edited by Endeavor

Share this post


Link to post
Share on other sites
Posted (edited)

Here is the result...

 

First, the unmodified wheel...

 

DSCN2721.jpg

 

 

The modified wheel

 

DSCN2755.jpg

 

 

The modified wheel from the back

 

DSCN2757.jpg

 

 

Now all I have to do is source some parts and build four more.

Edited by Endeavor

Share this post


Link to post
Share on other sites

Glad to be of help!

One other thing - I screwed the rim parts together at every step (not just clamped), that enables checking that the assembly fits together without gaps.

 

My rims are in red plastic. My green workshop carpet looks red by the time I've finished 5 rims....  There's a lot of plastic to get rid of.

 

If you look at my picture again - I turned down the top of the tyre valve to get a more realistic profile.

Share this post


Link to post
Share on other sites
Posted (edited)
6 hours ago, Jo NZ said:

 

One other thing - I screwed the rim parts together at every step (not just clamped), that enables checking that the assembly fits together without gaps.

 

That's the plan.  At this point the wheel is just "a proof of concept".  It, and the additional wheels, will be built and finished to a higher standard.

 

Nice work on the tire valve.  The Pocher part has to have been sourced from a supplier who made it for a very different purpose.

 

Thanks again.  Your help is greatly appreciated.

Edited by Endeavor

Share this post


Link to post
Share on other sites
Posted (edited)

 

This is a Touring bodied 8C 2300 Alfa Romeo.

 

image.jpg

 

 

This is a well built Pocher Touring bodied 8C 2300 Alfa Romeo.

 

image.jpg

 

 

Here is another Touring bodied 8C 2300 prototype

 

3_A.jpg

 

And here is the Pocher

 

image.jpg

 

Another prototype

 

image.jpg

 

 

My objective is to build a K73 Alfa that is a more accurate representation of a 8C 2300 Touring Spyder. There are significant differences among the three prototypes - including the grill shells, but those differences pale in comparison with the differences between an OOB Pocher K73 and a real Alfa.

Edited by Endeavor

Share this post


Link to post
Share on other sites

 

First Stage Body Modifications

 

The stock K73 body is shown in the photograph below.  It is very different than the bodies of the prototypes.  Every panel will have to be modified.

 

image.jpg

 

 

The K73 cowl is too long. The excess length lies between the louvers and the door.  This photo was taken after I cut the seat from the body and removed a 7.5mm vertical section from the cowl.

 

The cowl was cut with a flush cutting handsaw.  The seat was removed with a hobby knife using the back side of the blade.

 

image.jpg

 

 

The K73 cowl is too wide at the cockpit. The cowl width at the firewall is correct.

 

A piece was cut from the center of the rear cowl section to reduce its width.

 

image.jpg

 

 

image.jpg

 

 

The narrowed rear section of the cowl mates almost perfectly with the front section of the cowl.

 

The modified cowl is still a bit longer and wider than the prototypes, but it’s better.

 

image.jpg

 

 

 

Share this post


Link to post
Share on other sites
Posted (edited)

Sectioned

 

The Pocher body is too tall.

 

The first two photos below show a 7.5mm horizontal section cut and removed from the sides of the front cowl section. The cuts were made through the louvers because the louvers are too tall and because this positions the shortened louvers correctly on the sides of the cowl.

 

image.jpg

 

 

The louvers on the cowl are poorly formed so they will be removed and replaced. 

 

image.jpg

 

 

Channeled

 

To reduce the height of the main body to match the height reduction of the front cowl section, I trimmed 7.5mm from the bottom edges of the body. You can see how all of the surgery changes the body in comparison to the OOB body.

 

The bottom section of the body that sits on the frame rails over the rear axle must be trimmed and the bottom of the door openings must be raised.

 

DSCN1045.jpg

 

 

image.jpg

 


I removed the well for the spare tires with a hobby knife, using the back side of the blade, cutting from the inside of the body. 

 

image.jpg

 

 

Comparison with this prototype shows that major work lies ahead.

 

image.jpg

 

 

The two sections of the cowl are attached.

 

image.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites

I love your MFH Alfa build but am so glad you are bringing this along as well. Few may go as far to alter the Pocher into an Alfa. But it is a definitive statement on methods for serious alteration of any large scale model. It all starts with precise measurements and you and Roy V have proven leaders in that field.

 

Thanks for sharing - Pocher addicts are along for the ride.:worthy:

Share this post


Link to post
Share on other sites
Posted (edited)

THE CHASSIS

 

I assembled the chassis, utilizing Model Motorcar leaf springs and front axle.  

 

In addition to the several adjustments required to properly assemble the Pocher chassis, I made two modifications when the frame was first assembled.

 

I drilled sixteen holes in the front crossmember to match the prototypes.  This is a common modification to the kit chassis made by many Pocher builders.  The holes were enlarged slightly after this photograph was taken.

 

image.jpg

 

 

I also moved the engine back 10mm, a change made many Pocher builders, and one described in detail by Paul Koo.  The only evidence of this change in the photograph below is the addition of four new holes for the engine mounts.

 

The Pocher screws that attach the body to the frame were replaced with bolts and nuts. 

 

Because the K73 body is flexible, asymmetric, and changes its shape when bolted to the chassis, it is essential to make all measurements, modifications, and adjustments to the body when it is bolted to the frame.  This ensures precise and symmetrical adjustments and modifications.

 

Below you see the modified body mounted on the chassis.  The sectioned section of the cowl is mounted on the frame in its original position.  The channeled section of the body is mounted flush with the bottom of the frame rails, 7.5mm lower than the kit's original position.  I trimmed the section of the body that sits over the rear axle so it fits level and flush with the frame.

 

DSCN1092.jpg

 

 

The firewall was trimmed to fit lowered cowl. Even without the additional work that will be undertaken later, after this initial trimming the firewall is a reasonably accurate representation of a prototype.

 

DSCN1084.jpg

 

 

The spare tire mount was attached to the fuel tank.

 

DSCN1099.jpg

 

 

Here it is with a stock Pocher Spyder.

 

image.jpg

 

 

I removed the panel under the spares.  

 

These photographs also reveal the warped body. This will be fixed later.

 

image.jpg

 

 

The spare wheel needs to be repaired.

 

image.jpg

 

 

The spare tire well will be modified before it is integrated into the body.

 

image.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites

I love what you're doing here!

Share this post


Link to post
Share on other sites
Posted (edited)

Second Stage Body Modifications.

 

The K73 cowl is wider than the prototypes at the dash board and the leading edge of the doors. The body becomes narrower as it flows back

behind the seat. The prototypes are very different; they are narrower than the K73 at the cowl and the bodies becomes wider as they flow back

behind the seat.  In contrast to the K73, the prototypes’ rear decks over the rear axle are wider than the cowl.

 

The prototype rear bodies are wider and flatter on top, and slant inward as they flow down from the deck to the frame.  In contrast, the K73 bodies are rounded, narrow on top,  and slant outward. 

 

In addition, the upper regions of the rear of the K73’s body (at 11:00 and 1:00 o'clock) bend in and out like a Coke bottle.

 

Major surgery is required.

 

image.jpg

 

ref_151_2.jpg

 

 

I began by filling the upper sides of the rear body with styrene sheet and Milliput to eliminate the “coke bottle” shape. This makes the rear section of the body heavy and rigid.

 

I removed the molded side trim and reduced the thickness of the body panels in front of, under, and behind the doors. The panels are not thin enough yet, but it’s better.  When combined with the earlier removal of 7.5mm from the bottom of the body, all of this work reduced the rigidity of the body and it became quite flexible.

 

Channeling the body lowered the door jams.  To prepare for raising the door openings, I removed the inner sections of the lower door jams.

 

image.jpg

 

 

 

image.jpg

 

 

The "coke bottle" shape of the upper part of the rear body was eliminated.

 

image.jpg

 

 

I glued styrene pieces into the bottom of the door openings so that, like the prototypes, the bottom of doors will be level with the bottom of bonnet side panels. The styrene pieces restored most of the rigidity that was lost by trimming the bottom of the body and thinning the styrene around the doors.

 

image.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites

A master class. You're doing a huge service to Alfa builders by just IDENTIFYING the problems and differences plus all the measuring to get these shapes and true dimensions.

 

I for one appreciate you making this available. :worthy:

Share this post


Link to post
Share on other sites
Posted (edited)

The photographs below provide the first glimpse of what the finished model will look like.   It remains to be seen if the final product will be a good representation of a prototype.

 

The OOB Pocher Monza radiator shell is almost the right height and length for the modified body (!). The OOB Spyder hood (bonnet) is close to the right length. The firewall is further back on the frame, but the Monza shell is longer than the Spyder shell and makes up for most of the increased distance.

 

The hood must be lengthened, thinned, and reshaped to fit the radiator shell and cowl.

 

I modified the doors, but they are still a poor fit, primarily because of their compound curves. If I am unable to modify them to fit correctly, I will be forced to scratch build new doors. The trailing edges of the doors and jams require work. The curved leading edges of the doors do not match the prototypes.

 

image.jpg

 

 

With the radiator installed in the shell, and the engine and firewall in place, you can see how the parts fit together. The engine is located back 10mm from the stock Pocher position, and in this photo is held in place temporarily by a stick because the front motor mounts do not reach the front cross member in its stock position.

 

The rear spring shackles reveal that the rear axle is slightly out of position in this photograph.

 

image.jpg

 

 

The camera angle hides most of the poor fit of the bonnet.

 

This photograph shows the problem with the doors more clearly and, also,  the results of reshaping the sides of the rear body.

 

The radiator shell can not be positioned this far back with the front cross member and radiator in the OOB position.

 

image.jpg

 

 

The radiator shell for the Monza kit is stock except that I enlarged the slots around the front grill and thinned the plastic a bit.  Notice that it is positioned further forward than in the previous photograph due to the installation of the radiator.

 

After taking these photographs and studying two reference drawings, I realized that I had to move the front cross member.

 

These photographs were taken before the front cross member was moved.

 

image.jpg

 

 

I was tempted to just fix the all the existing fit problems and leave it in this state.

 

image.jpg

Edited by Endeavor

Share this post


Link to post
Share on other sites

Thanks for relaunching this project on the forum. I will be following along. Thank you for posting so many details too - this will a great reference for other Alfa builders!

 

Rich

Share this post


Link to post
Share on other sites

Wow! Great work on the wheels and the body. This is next level stuff. You have a good eye for spotting differences in the 1:1 vs the pocher.

Can I ask you if you have a technique for measuring or is there any eyeballing going on?

It looks so much sleeker and lower, I have never seen an alfa i real life but it surely looks the part. Great stuff!

 

Terje

Share this post


Link to post
Share on other sites

Massive improvements after massive amounts of work. Will you alter the hood panels or scratchbuild new? It may actually be easier and thinner material can be used - like brass.

Share this post


Link to post
Share on other sites

I moved the front crossmember that supports the radiator back 8.5mm. This moves the radiator and the radiator shell to more closely resemble the prototypes and reduces the gap created when the engine is moved back 10mm.

 

The top frame rail in the photograph below is unmodified.  The bottom frame rail in the photograph shows that I removed one half of the square molding that positions the cross member by fitting into its center.   In its new position, the leading edge of the crossmember fits against the back edge of what remains of the molding.

 

 

image.jpg

 

 

To achieve a perfect fit for the cross member, I cut two small notches in the leading edge of the cross member where it meets the frame rails and spent considerable time filing and adjusting.  Because the height of the rails is greater in the cross member's new location, the rear of the crossmember needed to be raised to fit tightly in its new position.  I added the two 1.5mm styrene shims you see in the photograph below, so that the cross member fits tightly within the rails.

 

image.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×