Cast iron bed crack - options

[DonInReno]

Well I finally had a few hours to play around with the machine and discovered the input shaft was a little bent, but on a happier note the binding in the lower end completely goes away when the bed is clamped halfway to being flat so I'm optimistic that grinding out the crack and brazing it will solve all the lower end problems :-)

Now about the input shaft - if you are squeamish it's better to stop reading now, because what I did to fix it is a little ugly!  I'm guessing whatever happened to crack the bed also put enough pressure on the hand wheel to bend the shaft.  The 562 has a beefy enough hand wheel that it wasn't damaged other than a newish looking scuff on the rim.

Again keep in mind the Juki isn't being sold to anyone and I'm not suggesting the following as a best practice.  I figured if the hand wheel is tough enough to bend the shaft in one direction it will most likely survive a tweak in the other to straighten things out.  It also seemed that it could be done in a way that doesn't put as much pressure on the rear bearing as the original damage did.

I held a dial indicator up to the rim to both accurately tell how much it's out and where the bend is.  Then two screws holding the wheel to the shaft were loosened and it was backed off the rear bearing 1/16" or so. The screws were tightened little more than finger tight so any impact wouldn't get fully transmitted to the bearing or down the shaft.  A block of hard maple was cut to be a firm fit between the hand wheel rim and the head.  Another chunk of hard maple was held to the top and gently tapped with a rather large hammer.  At least for me it's easier to judge a gentle tap with a big one rather than a big hit with a small hammer.  

After a hit the wedge block was removed and the rim checked for movement....after three or four increasingly stiff taps a little movement showed up - maybe only .002", but it moved.  I kept tapping with about the same force, checking the movement each time, until the hand wheel rim was within .005" runout - close enough that it can't be easily felt or noticed.

Spinning the wheel on the shaft it seems none the worse for wear. I also wasn't going to be heartbroken if it didn't survive since a replacement pulley was found in the return/scratch and dent rack at the local Summit Racing wearhouse.  For $30 this aftermarket power steering pulley feels good in my hand, is clear powder coated, and provides about a 60% speed reduction.  I'll press in a steal sleeve, drill it out to shaft diameter and tap holes for two new set screws.

Now the biggest decision is what color and texture to repaint everything.  Hammered Juki green like the original finish?  A high gloss cream or off white color looks good to me....that's a long weekend of sanding and filling the body just to prep it....Idonno.  It looks like some resellers on eBay are mixing Rustoleum hammered silver and a little black - doesn't look bad, but reminds me of a drill press. Lol

Edited January 28, 2018 by DonInReno

[DonInReno]

I’m getting closer to brazing the crack.  

The bed was stripped fairly easily. The only hang up was a single set screw in the stitch length gizmo and holy cats was it tight.  Giving a good-fitting screw driver bit a hammer smack didn’t do anything to loosen it up.  Then the housing the set screw was in was heated to about 200 degrees, but nothing.  Then it was heated till the oil started to smoke and nothing.  Another smack to the screwdriver bit and it finally unscrewed. 

Then the lower and upper were separated, paint on the bed was stripped and the crack is being ground out with a carbide burr.  The closeup shows how the crack shows up as a fairly dark line - you just have to keep grinding and chasing the line until down below the crack.  Luckily it doesn’t go clear through the bed, but about 2/3 to 3/4 the way through.   I still have a bit more grinding, but a good quality carbide burr seems to make this job much easier.

thats all for now...

[CowboyBob]

Here's a before & after,we used electric arc w/a nickle rod.

welded Adler.pdf

[Pintodeluxe]

As far as paint color... Rustoleum Hammered Rosemary is a dead ringer for the factory LU-562 and LU-563 color.  I found it in stock at my local Home Depot, but it can be ordered online as well.

Edited October 24, 2018 by Pintodeluxe

[SARK9]

Alas, the hammered rosemary seems to have been discontinued. There may yet be odd cans on high shelves that have not been sold here and there, but none of the Rust-oleum sites online show this as a current color offering. If there is any retail stock remaining, I certainly can't find it.

-DC

. 

[DonInReno]

 

On 10/24/2018 at 10:46 AM, Pintodeluxe said:

far as paint color... Rustoleum Hammered Rosemary is a dead ringer for the factory LU-562 and LU-563 color.  

I’ll definitely keep my eyes open for that color!

 

On 10/24/2018 at 10:09 AM, CowboyBob said:

Here's a before & after,we used electric arc w/a nickle rod.

welded Adler.pdf

Wow that was quite a break!  Seeing some of the machines you and other sewing outfits have patched back together gave me the somewhat misguided confidence to fix the crack in this one!  By the time I bought the carbide burr, bronze rod, welding blanket, paint stripper, 6 colors of paint, and all the hours reading up and practicing it would have been cheaper just to toss it in the spare parts bin and buy another!  That reminds me to stop by the metal yard and buy some angle to keep it lined up during brazing. Lol

[chrisash]

Probably very nieve but could you not put some baces screwed into the clear sides of the split on either side, if heated before fitted they would shrink and tighten when at room temp

If one end fixed before heating you can measure the expansion prior to fitting to be able to close the crack

Maybe a silly solution but seen it done before on other equipment

Edited October 26, 2018 by chrisash

[DonInReno]

I’m not sure if anyone has an easy crack detection dye or method, but after the visible cracks were gone I was sure the cracks continue but are very fine....

Reading up on crack detection the systems that use strong magnets and fine iron powder got me to thinking and a magnetic base off a dial indicator base seemed to work really well clamped on the other side of the bed from where the grinding was taking place.  With the two poles on either side of the crack the crack became the divide and iron fines highlighted    It seemed to highlight cracks another 1/16” into the iron from what could be seen without the magnet. I’m more confident I’ve ground down far enough - looking forward to patching it up tomorrow.

[DonInReno]

7 hours ago, chrisash said:

Probably very nieve but could you not put some baces screwed into the clear sides of the split on either side, if heated before fitted they would shrink and tighten when at room temp

If one end fixed before heating you can measure the expansion prior to fitting to be able to close the crack

Maybe a silly solution but seen it done before on other equipment

 I’m sure the machine could have had a brace of one kind or another and worked fine, although it would have always bugged me.   I’ve been enjoying welding and machinist videos lately, especially the cast iron stuff, and for the most part I’m hoping to get somewhat proficient at cast iron repairs since it pops up again and again in old equipment of all kinds.  Eventually I’d like to weld some cast iron with nickel rod, but for now I’m focused on tig and gas brazing.

[carlcarl]

Hello there,

 I’m a newbie in sewing machine world but I’m not in welding world.

i don’t know what you have as far as welding equipment but there is a GMAW wire

you should seriously consider

Crown Alloys 44-30 mig wire

It’s not cheap at 70-80 per 2lbs spool, but it’s going to be a more forgiving than any GTAW approach where pre and post heat are critical, and you get a weld that is rather difficult to grind or clean up once your done.

 I’d still preheat (I bought a used gas bbq just to use as a preheater!) 44-30 can be filed or ground if you want to clean it post weld.

I’m also a fan of brazing cast iron, but I haven’t done any of that since I bought a spool of the 44-30.  

Best of luck

Carl