Mike Donnerstag | 15/07/2020 10:29:17 |
![]() 231 forum posts 53 photos | I recently purchased a Myford Super 7 power cross-feed apron, but unfortunately the dovetail was damaged in transit, with a small chip around 5mm long and 2mm wide removed from the top edge, as in the photo below. My questions are: 1) Is the saddle still usable? Am I right to assume that it isn't usable as-is, as it would result in wear to the gib? 2) Can it be repaired? If so, should it be brazed, silver-soldered or welded? I seem to remember having read somewhere that weld on cast iron can create brittle areas and therefore braze is better. Am I right? Many thanks, Mike |
John C | 15/07/2020 10:37:46 |
273 forum posts 95 photos | 1. The saddle is still useable. The loss of bearing surface is negligible. The gib will only be damaged if it snags on a sharp edge of the hole. See below. 2, Yes. I would use an oilstone to smooth any rough edges, clean thoroughly and reassemble. Good news I hope! John |
Journeyman | 15/07/2020 10:49:08 |
![]() 1257 forum posts 264 photos | Perhaps fill the chip with one of the metal bearing epoxy fillers - JBweld or Devcon Steel for example. Then shape back to match original profile. May prevent the odd piece of swarf getting in there and causing damge. John Edited By Journeyman on 15/07/2020 10:49:28 |
Dave Halford | 15/07/2020 11:17:10 |
2536 forum posts 24 photos | If you decide to fill, find a piece of flat metal like a Stanley type blade to fit under the dovetail. Coat the plate/blade with 3 or 4 layers of wax (car polish will do) don't use oil, don't use any fewer coats. Apply your choice of filler to the surfaces of the hole. Clamp the plate/blade wax side to the dovetail. Add any more filler required to fill any voids and scrape the excess off the top with another blade. This will cut down any shaping required to next to nothing. |
Hopper | 15/07/2020 12:12:24 |
![]() 7881 forum posts 397 photos | Any kind of welding or brazing or even silver soldering is likely to cause distortion and a bigger problem than you already have. Smoothe off the edges and carry on. I would not even bother with any kind of filler. Too likely to get swarf embedded in it. |
blowlamp | 15/07/2020 12:53:45 |
![]() 1885 forum posts 111 photos | You might be as well to check the saddle for twist if it's had a knock. Place it on the lathe bed with a finger resting lightly in the middle to keep it from rocking, whilst tapping in each corner with your best knuckle. Any area that gives other than a dull thud when this is done is probably not in full contact with the bed and will need sorting out.
Martin. |
Pete Rimmer | 15/07/2020 19:38:16 |
1486 forum posts 105 photos | Make a burr file and get rid of any high spots then just use it. Take an ordinary thin flat file and rub it on a stone a bit to take the edge off the teeth. Now run the file flat across the dovetail surface. It will only cut high spots and leave the way surface unharmed. |
Mike Donnerstag | 16/07/2020 19:10:18 |
![]() 231 forum posts 53 photos | Great advice - thanks to all who posted. I did order some JBWeld, though I will probably just leave it smoothed. The whole saddle was quite black, perhaps leftover from some kind of rust remover? I tried to shine up the non-bearing surfaces in several ways, in the following order, moving from mild to more agressive, all of which lubricated with WD40 or white spirit: 1) a slipstone to remove any high spots, though this was very of course very slow in removing the 'black' surface 2) green scotchbrite, which didn't do much either 3) fine emery cloth, backed with a small square of wood, which did slowly remove the black surface, leaving the silver cast iron I assume it doesn't really matter how I make the non-bearing surfaces more cosmetically appealing, though does anyone have a quicker way that they use for all flat cast iron surfaces? Citric acid perhaps? Mike |
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.