In this post I’ll cover the final finishing and assembly of the mixer.
Polishing the Metal and Bakelite Parts
Luckily, on this mixer the shiny metal parts, principally the planetary hub, were only dirty and not damaged or scratched. Finishing these was a straightforward process of cleaning/degreasing followed by polishing with a soft cotton buffing wheel on a bench grinder and some super fine finishing compound. I used Dialux Bleu compound for most of the metal polishing. This compound also proved excellent for polishing the black Bakelite parts back to a deep shiny lustre.
Finishing the Painted Mixer Body
The body of the mixer is made of cast aluminium in three pieces; the base, the motor compartment and gearbox housing, and the top (gearbox) cover. Because it is all metal, I decided to have it powder coated for maximum durability in a slightly off-white colour (specifically, a Dulux PG288 powder colour called “Chalk USA”). I had previously had another mixer body, a rare Kenwood A200, powder coated in the same colour, and had learned a couple of important things about the process. Firstly, be very specific about what you want masked off, and secondly, get some sacrificial screws for the small threaded holes, especially the blind ones, so that sand blasting grit does not get into them. This is almost impossible to remove completely, and can cause big problems when you come to assemble the mixer. After blasting, the screws should be removed and replaced with silicone plugs for the powder coating process, which the powder coater should have available. The small machine screws used for securing the gearbox, ring gear, cable clamps etc. in the A700A are steel “cheesehead” size 4 BA thread screws of various lengths. These are mainly used by model makers now. I found an excellent online supplier, BA Bolts in the U.K. I ordered several sizes and used them to replace the originals in the final assembly. I used the originals as the sacrificial screws for the sand blasting.
This time round I learnt another important lesson about powder coating these old Kenwoods – namely how difficult it is to remove all that old grease! I thought I had the metal parts all cleaned out after flushing with copious quantities of dichloromethane, hexane etc., and finally washing with detergent and hot water.
However, when the parts were heated in the powder coating oven, grease that still remained in nooks and cranies melted and ran over the powder finish. One particular area of trouble was the brass bearing that the planetary drive shaft passes through (visible in the above photo), but grease also ran out from screw holes and even from under the name plate under the base. In the end I think the poor powder coater had to redo the job 3 times! Next time I’d be more particular with cleaning problem areas, and possibly instruct the coater to preheat the parts first to see if any grease runs develop.
Reproducing the Kenwood Logo
As I mentioned in part 1, this particular early model A700A mixer had “Kenwood” printed in black lettering on the mixer body (see photo below). Most models that you see have the later “Kenwood Chef” logo variant. There was someone on eBay selling reproduction “Kenwood Chef” decals, but I wanted to reproduce the original logo. Also, the reproduction decals were printed on clear vinyl with a clear border, and I wanted cut-out black vinyl lettering to give it a clean painted-on look.
Working with a photo of the original logo as a template, I traced the logo in Adobe Illustrator to produce a vector art version, and then spent some time adjusting it to compensate for angles and curvature so that it accurately reproduced the original when printed and applied to the mixer body surface. I then chose a printer that was able to reproduce it in cut vinyl lettering, in this case White Tailed Grizzly (Omaha Nebraska). The end result was excellent, even though the printer had slightly enlarged the logo for reasons unknown.
The Speed Control Knob
The paint in the engraved numbering of the speed knob had worn away over time, and anything that was left was removed by the buffing up of the Bakelite on the polishing wheel.
Luckily, restoring the fill-in paint is very easy to do with a Markal “Lacquer-Stik”. Just work it in, wipe it off and…
The gearbox comprises the entire top arm of the mixer, and is packed with grease. Over time, oil separates from the grease and tends to leak out past screws, the gearbox cover, and worst of all down into the motor compartment. Oil gumming up the motor brushes was what ultimately stopped this mixer from working. Consequently I was careful to replace all seals, and try and improve the sealing where possible. I purchased a seals kit from an eBay seller which included the main gearbox cover o-ring, and the various cork and felt gaskets just like the originals. However, in several places I improvised my own gaskets from nitrile rubber sheet as a more durable alternative (I hope!). In particular, I cut a nitrile gasket for the main seal between the motor and gearbox, and put nitrile washers under the motor bolts as shown in the photo below.
Reassembly of the gear train is a straighforward reversal of the disassembly process (see part 1), remembering to re-fit all the washers and shims. I used a silica based synthetic food grade grease (CRC NSF H1) as this type of grease is supposed to have good resistance to oil separation. Unusually, it’s completely clear and transparent – which keeps it all looking clean on the inside as well!
After that it was just a case of putting the top cover on, refitting the blender attachment parts and the planetary hub, and standing back to admire this wonderful machine in all its restored beauty! Oh, and of course plugging it in to see if it all works – which it did! So to finish, here are a few more photos of the finished machine – Kenwood Chef, serial number 91831. I hope you’ve enjoyed reading about this project.