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I'm building an Association replacement Pannier chassis and have a persistent problem with the frames bending slightly when soldering in the spacers. I've tried redoing them a couple of times and always get the same (or similar) result - I check the spacer sizes are correct, frames are straight etc. but after the last spacer is soldered in they come out of the jig bent to one side at one end. I've got it down to about a 0.4mm bend along the length of the chassis, but it's not right and I don't know what I'm doing wrong. 

 

Is it just me, or is this a common phenomenon with expansion/contraction of the frames or something similar? 

 

Regards,

 

Chris

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Are you using horizontal and vertical spacers? A picture (or more) would aid our understanding and help with feedback.

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Are you using horizontal and vertical spacers? A picture (or more) would aid our understanding and help with feedback.

Sorry, don’t have a photo to hand but will try for one when next in the workshop. I’m using horizontal PCB spacers milled to fit in the pockets provided in the chassis kit, and assembling it in the jig provided. The frames seem to be OK in the vertical but pull away to one side in the horizontal towards the rear of the chassis (which is where the last spacer was soldered in).

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Sorry, don’t have a photo to hand but will try for one when next in the workshop. I’m using horizontal PCB spacers milled to fit in the pockets provided in the chassis kit, and assembling it in the jig provided. The frames seem to be OK in the vertical but pull away to one side in the horizontal towards the rear of the chassis (which is where the last spacer was soldered in).

 

I can only think there are hidden stresses in the frames which show up when soldered. I checked the artwork again and there is no issues with the jig. So try assembling it upside down in the jig (this was designed to be possible), soldering the spacers in a different order and so on. When all else fails you could put a slight bow in the frames in the opposite direction to the probam you have but you will have to be careful not to distort them.

 

Chris

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Emphatically, a decent vice is required. Quite expensive, but worth every penny.

http://www.cooksongold.com/Jewellery-Tools/Precision-Bench-Vice-prcode-997-1080

I could not produce my engines without a similar version.

 

Tim

 

How does the "bench plate" fix to the bench? Does it need to have a recess cut in the bench or is it a clamp on device. I need one to fix to the kitchen table without upsetting anyone.

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How does the "bench plate" fix to the bench? Does it need to have a recess cut in the bench or is it a clamp on device. I need one to fix to the kitchen table without upsetting anyone.

Fully agree with Tim, a good vice and a selection of descent quality files are crucial. The base plate screws down. I have an extra baseplate on my portable workbench which I take to shows or when I want to work in the house as opposed to the workshop - an ideal solution if you are going to be based at the kitchen table. A piece of cheap camping mat rubber underneath will stop it slipping or marking

 

post-1074-0-28945900-1524145238_thumb.jpg

 

post-1074-0-66797700-1524145261_thumb.jpg

 

Jerry

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I can only think there are hidden stresses in the frames which show up when soldered. I checked the artwork again and there is no issues with the jig. So try assembling it upside down in the jig (this was designed to be possible), soldering the spacers in a different order and so on. When all else fails you could put a slight bow in the frames in the opposite direction to the probam you have but you will have to be careful not to distort them.

 

Chris

 

Thanks Chris - I'm confident it's not the jig and is definitely something to do with my cack-handed assembly. I'm wondering if it's something I've done with the centre spacer, which is the one I've never removed and replaced so it could definitely be a problem with the order of assembly. I'll try your suggestions and see how I get on...

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Sorry, don’t have a photo to hand but will try for one when next in the workshop. I’m using horizontal PCB spacers milled to fit in the pockets provided in the chassis kit, and assembling it in the jig provided. The frames seem to be OK in the vertical but pull away to one side in the horizontal towards the rear of the chassis (which is where the last spacer was soldered in).

can you confirm you have added vertical spacers please 

 

Nick

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Thanks for the tip on the little vice. I have a small vice but I could really do with a smooth jawed version. That and some diddy reamers! Has anyone got a picture of how the vacuum cylinder fits on the sample kit? Appears to sit at a slight angle as it doesn't want to sit flat. Hence the fold line I'm guessing. The instructions aren't too clear on that, just says attach it :) It's going together well though! Nice design I must say :)

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can you confirm you have added vertical spacers please

 

Nick

No, just 3 horizontal spacers as shown in the drawing on the instruction sheet PDF document.

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Fully agree with Tim, a good vice and a selection of descent quality files are crucial. The base plate screws down. I have an extra baseplate on my portable workbench which I take to shows or when I want to work in the house as opposed to the workshop - an ideal solution if you are going to be based at the kitchen table. A piece of cheap camping mat rubber underneath will stop it slipping or marking

 

attachicon.gifIMG_3918.JPG

 

attachicon.gifIMG_3919.JPG

 

Jerry

 

Thanks Jerry ~ just what I wanted to know! I wonder if Edward Sissling stocks them.

 

Roger

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No, just 3 horizontal spacers as shown in the drawing on the instruction sheet PDF document.

I have just checked the sketch and you have followed the instructions,  however most other chassis have down vertical supports see the 03/04  or 4f etc   I think this may resolve your problem

 

keep trying it took me many years to make  a working (if still unfinished) chassis 

 

Nick

Edited by nick_bastable

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It took me nearly 30 years to make the first working chassis I was pleased with. It took a couple of months to make the second one. Lots of lessons learned.

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I have just checked the sketch and you have followed the instructions,  however most other chassis have down vertical supports see the 03/04  or 4f etc   I think this may resolve your problem

 

keep trying it took me many years to make  a working (if still unfinished) chassis 

 

Nick

 

I am not sure whether vertical spacers will help with the chassis bowing in the horizontal direction. But there is certainly potential with this chassis to make both the central and rear spacers longer if you prefer. That should make it less flexible.

Edited by Chris Higgs

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I am not sure whether vertical spacers will help with the chassis bowing in the horizontal direction. But there is certainly potential with this chassis to make both the central and rear spacers longer if you prefer. That should make it less flexible.

Thanks Chris - to be honest I’d not thought of that but it does sound worth a try, although I’m still sure it’s my technique that’s somehow at fault.

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I'm building an Association replacement Pannier chassis and have a persistent problem with the frames bending slightly when soldering in the spacers. I've tried redoing them a couple of times and always get the same (or similar) result - I check the spacer sizes are correct, frames are straight etc. but after the last spacer is soldered in they come out of the jig bent to one side at one end. I've got it down to about a 0.4mm bend along the length of the chassis, but it's not right and I don't know what I'm doing wrong.

 

Is it just me, or is this a common phenomenon with expansion/contraction of the frames or something similar?

 

Regards,

 

Chris

I've yet to build one of these, so no direct experience, but it does sound like it might be a heat expansion issue. A more powerful iron might be able to make the frame to PCB joint quicker, so there is less time for heat to travel along the frame side, expanding it. Confining most of the heat to the joint area itself. Are you soldering all the spacers to one side first, then soldering them to the other side frame? Could putting some on one frame and some on the other first help, before joining the two sides together? To me it seems that the frame will bow so that the frame to PCB joints soldered last will be on the inside of the bow as it cools and contracts. Leaving plenty of time to cool between making each joint joining one side to the other could also help, as could heat shunts clipped on the frames each side of the PCB.

 

Mim

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Are there any particular tools that are useful for 2mm and may not be in a regular kit used for 4mm plus?

In addition to those which have been already mentioned, all of which I heartily endorse, I find a small hand vice such as sold by Squires (see page 32 of their catalogue).  It is invaluable for holding small components while you file them and particularly for holding small etched parts while you remove the last remnants of tags.  For the latter job a fine India stone is also invaluable as it won't snag and distort the part in the way a file might.

 

Jim

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I've yet to build one of these, so no direct experience, but it does sound like it might be a heat expansion issue. A more powerful iron might be able to make the frame to PCB joint quicker, so there is less time for heat to travel along the frame side, expanding it. Confining most of the heat to the joint area itself. Are you soldering all the spacers to one side first, then soldering them to the other side frame? Could putting some on one frame and some on the other first help, before joining the two sides together? To me it seems that the frame will bow so that the frame to PCB joints soldered last will be on the inside of the bow as it cools and contracts. Leaving plenty of time to cool between making each joint joining one side to the other could also help, as could heat shunts clipped on the frames each side of the PCB.

 

Mim

 

Thanks for that - I honestly can't remember what order they were added as it was built a few months ago, left to one side (with all the other projects) and I then recently tried to fix it. I'm pretty sure I'd have done them end-to-end, i.e. both joints on one spacer, then then next spacer, etc. Your conjecture about the direction of the bowing being on the inside of the last joint soldered certainly fits with what I'm seeing. Maybe time to try a few heat sinks if I get time this weekend.

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I'm building an Association replacement Pannier chassis and have a persistent problem with the frames bending slightly when soldering in the spacers. I've tried redoing them a couple of times and always get the same (or similar) result - I check the spacer sizes are correct, frames are straight etc. but after the last spacer is soldered in they come out of the jig bent to one side at one end. I've got it down to about a 0.4mm bend along the length of the chassis, but it's not right and I don't know what I'm doing wrong. 

 

Is it just me, or is this a common phenomenon with expansion/contraction of the frames or something similar? 

 

Regards,

 

Chris

 

I have encountered your frame issue a few times in the past in a variety of scales. Almost inevitably it has proved to be a frame spacer not truly square or sitting dead square in the correct position, especially with the etched/bent 90degrees type. Occasionally it has been the frame twisted or bent a bit, but not often. The errors have been small, tiny in some cases, but enough to throw things out. Your description says to me that one or more of the PCB frame spacers is not aligned correctly on each opposing frame, a mis-match between the sides.

 

Could I suggest you remove all the spacers, clean up the frames, make sure all bits are true, and start again. Sighting along the flat sides of the frames will show up the slightest kink/twist, which is all such a problem needs to exist. Placing them back-to-back will show any differences in spacer location points. It can be slight enough that they will still drop into the jig. I have found that the spacers don't need to be a very tight fit as if there is the slightest error in them this will stress/twist the frames. I take it you are using the PCB frame spacers from shop 3?

 

Izzy

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I have encountered your frame issue a few times in the past in a variety of scales. Almost inevitably it has proved to be a frame spacer not truly square or sitting dead square in the correct position, especially with the etched/bent 90degrees type. Occasionally it has been the frame twisted or bent a bit, but not often. The errors have been small, tiny in some cases, but enough to throw things out. Your description says to me that one or more of the PCB frame spacers is not aligned correctly on each opposing frame, a mis-match between the sides.

 

Could I suggest you remove all the spacers, clean up the frames, make sure all bits are true, and start again. Sighting along the flat sides of the frames will show up the slightest kink/twist, which is all such a problem needs to exist. Placing them back-to-back will show any differences in spacer location points. It can be slight enough that they will still drop into the jig. I have found that the spacers don't need to be a very tight fit as if there is the slightest error in them this will stress/twist the frames. I take it you are using the PCB frame spacers from shop 3?

 

Izzy

 

Thanks for that - yes, I'm using the shop 3 PCB spacer strip. 

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Emphatically, a decent vice is required. Quite expensive, but worth every penny. http://www.cooksongold.com/Jewellery-Tools/Precision-Bench-Vice-prcode-997-1080

I could not produce my engines without a similar version.

Tim

Cooksons have a free postage offer on this weekend. I have just ordered one of these vices using it. (No connection other than as a customer).

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Cooksons have a free postage offer on this weekend. I have just ordered one of these vices using it. (No connection other than as a customer).

Must register to buy, place of birth mandatory; what!!!

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Must register to buy, place of birth mandatory; what!!!

 

So, register with "Trumpton", and a birthday of 1st Jan 1950, or similar nonsense data.

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Could any of the panel please furnish me who a copy of the Stephen Harris instructions for 16T opens, plate, catfish and grampus please?

 

The originals were put in a very safe place before emigrating...

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Could any of the panel please furnish me who a copy of the Stephen Harris instructions for 16T opens, plate, catfish and grampus please?

 

The originals were put in a very safe place before emigrating...

 

I think I've got instructions for all these. Will scan them for you tomorrow.

 

Andy

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