Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Machine Shop
Date: Tue, 4 Mar 2025 23:04:14 -0500
Organization: A noiseless patient Spider
Lines: 58
Message-ID: <vq8ifu$295bb$1@dont-email.me>
References: <IlHFO.77208$1m96.61123@fx15.iad> <vc7gsb$2brsl$3@dont-email.me>
 <FwYFO.93926$v8v2.91066@fx18.iad>
 <i5vgej9tm9fu3oosoukjjqovmqb4rp0onj@4ax.com>
 <Op1GO.23868$6a33.16569@fx33.iad> <vcanav$35vab$2@dont-email.me>
 <vd29u9$3sdmh$2@dont-email.me> <vd3pnp$71lk$2@dont-email.me>
 <jLrXO.537817$WOde.88257@fx09.iad> <vglnak$3aja7$3@dont-email.me>
 <F%puP.115483$1Fwa.96971@fx01.iad>
 <4edkrj13v11bkgfpmgcr58psf6v64j906f@4ax.com> <vpdim4$54ql$3@dont-email.me>
 <g4dcsjp0861h473qm48glmva215n16bhv7@4ax.com> <vq63v8$1o30s$1@dont-email.me>
 <vq7bpe$1v155$3@dont-email.me> <vq7mft$212bq$1@dont-email.me>
Reply-To: frkrygow@gmail.com
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Wed, 05 Mar 2025 05:04:16 +0100 (CET)
Injection-Info: dont-email.me; posting-host="e45c4557a9a8cc0980efe60bc42cb36a";
	logging-data="2397547"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/oRCXCKriTrKMxoOQTwQNgodDaKJ8NYK0="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:1xTcdIq3UWAbp+AG3hTSxzIWtLM=
In-Reply-To: <vq7mft$212bq$1@dont-email.me>
Content-Language: en-US
Bytes: 3824

On 3/4/2025 3:06 PM, AMuzi wrote:
> On 3/4/2025 11:03 AM, Frank Krygowski wrote:
>> On 3/4/2025 12:44 AM, AMuzi wrote:
>>>
>>> For a typical dent, this Waterford for example:
>>> http://www.yellowjersey.org/wfd12a.jpg
>>>
>>> the tube is rolled to reform the greater part of the deformation:
>>>
>>> http://www.yellowjersey.org/wfd12b.jpg
>>>
>>> then the remaining low spots are filled with polyester bondo or with 
>>> metal (brass, silver, lead. I use lead):
>>>
>>> http://www.yellowjersey.org/wfd12c.jpg
>>>
>>> and finished:
>>>
>>> http://www.yellowjersey.org/wfd12e.jpg
>>
>> Could you explain what's meant by "the tube is rolled"? As I said 
>> earlier, I'd thought the first step would be pushing a mandrel through 
>> (if the dent was in the seatpost) to partially push out the dent. Of 
>> course, that wouldn't work except on a seat tube, and I suppose would 
>> still require filling. Are you skipping that step entirely?
>>
>> BTW, my antique BMW has a slight dent in the top of the gas tank, 
>> apparently from something falling onto it. I've heard of "paintless 
>> dent repair" for car bodies and wondered about it, but never looked 
>> deeply into it. I gather that some skilled body workers can do pretty 
>> well at pushing dents back out from the underside.
>>
> 
> Can't generally fit anything inside a bicycle frame tube in any 
> reasonable time. Taking a frame apart is more than a magnitude of labor 
> greater than the cost of a tube. Once apart, you'd just replace it 
> rather than repair.
> 
> Here's one set of steel blocks for rolling dents.
> 
> http://www.yellowjersey.org/photosfromthepast/den24a.jpg

So how exactly are the blocks used? Are the blocks tightened in place 
and rotated around the tube?

> 
> I have various diameters. On oval tube of course there are limited 
> options. I generally don't take those jobs except where the dent is 
> minimal:
> 
> https://www.yellowjersey.org/photosfromthepast/denw25a.jpg

It occurred to me after posting that forcing a mandrel inside the tube 
might cause some of the metal around the dent to bulge outward. I can 
see why you wouldn't want that to happen.

-- 
- Frank Krygowski