Renovating/servicing a Rapidor hacksaw

[brightspark]

Sounds like you need an hydraulic lift there fella

let me guess errr u might be the person that just might have one 4 sale

 

[brewdexta]

Sounds like you need an hydraulic lift there fella

Do you possibly have something that could help?

 

[Shox Dr]

Do you possibly have something that could help?

Well since you ask...

 

[brewdexta]

While the paint is drying on the suds tank and pulley guard, I thought I would test the suds pump.

Well it pumps, but out of an orifice that I don't think it was designed to do. There is a hole in the casting between the mounting bolts, looks like combination of a fault in the casting and corosion although there is a possibility it is a bypass in case the suds pipe tap is closed as the pump is cam activated off the main spindle and operates whenever the saw is moving.

Here's what it looks like. The suds tank sits under the saw with the pump in it. The piston is pushed down by a pushrod from the cam on the saw's main spindle. You can see the hole in question between the mounting holes. The proper exit is on the left.

Here's a close up of the hole

Here you can see the inlet hole at the bottom, this is blocked by a ball bearing on the down stroke, the spring enables the piston to return and follow the cam

The outlet on the left has another ball bearing in, this one acts as a none return valve it, but doesn't want to come out and can't be pushed out from below.

At the moment, all the flow comes out of the hole in the casting rather pushing past the none return valve. So not sure if the none return valve is stuck and/or the hole in the casting is too big or shouldn't be there. The only reason I haven't welded it up already is that I was thinking what happens to the pressure if the saw is moving and the tap on the duds pipe is shut?

Anybody seen a pump similar to this before I weld it up? I can always drill a hole again however thought I'd ask first.

Cheers
Andy

 

[rtbcomp]

Is the ball that won't come out held captive by peening the edge of its housing over?

 

[brewdexta]

Hi Rtb

Not a far as I can see, its in the outlet shown on the left and it has an internal screw thread to take a pipe, it sits at the bottom of that hole, probably held on place by similar 50 year old gloop that the rest was, the difference here is that I can't get to push it out from underneath. I could possibly shift with some air, carefully dodging the high velocity bullet ti could become

Cheers
Andy

 

[brightspark]

u could try warming it up and giving it a tap failing that last resort drill the casting underneath with a small hole and punch the ball bearing out and fill the hole afterwards

 

[MattF]

Not a far as I can see, its in the outlet shown on the left and it has an internal screw thread to take a pipe, it sits at the bottom of that hole, probably held on place by similar 50 year old gloop that the rest was, the difference here is that I can't get to push it out from underneath. I could possibly shift with some air, carefully dodging the high velocity bullet ti could become

Screw the hose coupler or a blanking plug into that outlet and use compressed air through the piston chamber. The bearing can't fly out that way. You could also just drop a bit of white vinegar down that outlet and let that work on the corrosion/crap overnight. It'd likely just drop out then.

 

[brewdexta]

I put some citric acid in the part of the pump that was causing problems and left it overnight. Seemed to do the trick, after a bit of prodding and swearing the ball bearing came out just as I was about to choose plan B - compressed air or drilling a hole.

The hole in the back still took all the flow with hardly any going the way if should so I guessed it was superfluous and welded it up after giving the thing a good clean and degrease and a made the hole a bit bigger so it was back bare metal, but I didn't want to make it too big and weld through into the chamber and have to bore it out. I can always drill a smaller hole later if its needed.

Trouble is that a new hole appeared below it, no sign of it before welding the first hole

So I cleaned that out and welded that too. Reinforces the probability that the original hole in the pump was there by accident rather than design.

Not sure if the casting is like a swiss cheese and more holes will appear but I gave it a good probe, tested it and it now pumps out of the right orifice so rubbed it down and degreased it again and give it a coat of zinc primer.

Also noticed that the 90 degree marks on the vice are way off. I tried it with both sets of swivelling jaws as they are interchangable. I'll check it with the saw running first before grinding the marks out and remarking.

I also got the guard back on today, needed some of the brackets tweaking to make sure it didn't foul the pulley in all clutch positions - note to self, in future do tweaking before painting! Fortunatel only a couple of scratches to touch up.

Also welded one end on the new tommy bar for the vice but made such a balls of it that I'm cutting it off and starting again.

Cheers
Andy

 

[breezer]

Question for all the rapidor fans out there...

What is the 'tank' under the crank for? Cleaned my saw up today and found a drain hole in there. The casting is obviously done to hold something and i presume this is a liquid but i cant think what as the suds tank is normally underneath the saw table.

Unless its just there for oil drips off the saw mechanism but it seems rather superfluous if so

Jim

 

[brewdexta]

I believe it is there to catch drips, mine was about half inch deep in oil when I got it.

I suppose if you had a penchant for machinary as industrial art and had a posh loft in Shoreditch you could use it to serve olives from

 

[breezer]

Mmmmmmm olives...

 

[brewdexta]

Mine hasn't got a drain hole, however the pin that drives the suds pump from the crank goes through the middle of that tray. So maybe the drain hole is just the hole where the pin goes if you had that feature?

 

[brightspark]

nice job seems a shame to get it dirty all i do with mine when it gets oily and dirty is cover the motor and electrics up .steam clean it off tape the moving parts up with masking tape and spray it with hammerite that i got from autojumble for a tenner for half a gallon it works for about 10 years the only service it recieves is clean the guide bars regularly and oil them and grease the crank bearings and conrod regularly the odd clean and thats it mantenance free

 

[MattF]

Those holes were likely slight casting flaws. A water based cutting fluid might well have corroded the casting too, making them worse. You can just see the start of pinholing in those first photo's you posted for that casting, where that second hole appeared. The heat from the welding will have finished that hole off.

Was all of the metalwork so clean when you got it, or have you blasted the metal after stripping it?

 

[breezer]

The hole in mine is in a different place and diagonal through the body.

Thing is theyre so old you dont know what came out of the factory and what was a later modification.

There are that many holes in different places yo onlg uncovef when yoj start scraping the years of muck off

 

[brewdexta]

Those holes were likely slight casting flaws. A water based cutting fluid might well have corroded the casting too, making them worse. You can just see the start of pinholing in those first photo's you posted for that casting, where that second hole appeared. The heat from the welding will have finished that hole off.

Was all of the metalwork so clean when you got it, or have you blasted the metal after stripping it?

I used a combination of stripping and chipping and a water based degreaser on the main body, if I had dismantled it completely I would have had it blasted but the old paint came off easy so I didn't bother. I had the guard and the suds tank blasted.

As Brightspark alludes too, its going to get covered in oil and get chipped so not much point going too far but if your going to do a job you may as well do it right. The deciding factor for me was that the spindle etc felt good with no play so no need to dismantle.

Cheers
Andy

 

[brewdexta]

Done a bit more, just about finished now.

Wired up a NVR switch by taking the old 3 phase switch, cutting out the old buttons and bolting in a ten quid NVR from fleabay

Before



After


Getting to all the oiling points can be awkward with small oild can, it made me dig into a pile of old oil cans I bought at a farm sale, this one seems to hit the spot, its about 2 foot long with a narrow spout. I need some oil and I'm not paying a fiver for 200ml of 3 in 1 oil. I'm guessing a light engine or gear oil should run down the oil points well enough - any suggestions on grade?





to give you an idea of scale the oil can is sat on the hacksaw vice.


Last job is to fit the suds tank, just waiting for a 1/4" BSP die so I can thread the pipe and move and elbow.



Cut a load of 50mm box with it today - nice and easy, just needed a touch of belt dressing.

Cheers
Andy

 

[Dev]

You never said but I take it the 90 degree marks matched up when you swapped the jaws?

 

[brewdexta]

You never said but I take it the 90 degree marks matched up when you swapped the jaws?

No, the vice marks didn't match up - I must admit very confusing as you would have thought at one time it must have been marked up square. Unless they have been swapped in the past?