Wonky cutting power hacksaw

[Thrashsmith]

Hi folks, wondering if someone can help with diagnosing a power hacksaw that's cutting a tad wonky...

Earlier I went to look at a Rapidor Manchester power hacksaw that's for sale, I know literally nothing about these things but to a novice it looked good - the blade was rising and falling at a perfect 90 degrees to the vise, the blade was in good condition, the blade was pretty tight, it cut nice and quiet...but it was mitreing at an angle back towards the vise.

The guy who's selling it had some scrap 20 x 20 x 3mm box so that's what I was testing it out on, the cuts were about 2mm out at the bottom of the cut.

Kinda frustrating because I quite liked the little thing and it was a good price. I didn't take any measurements the cut capacity was about 14 x 6 inches.

Cheers in advance for any help.

 

[Spark plug]

2mm out of square over 20mm is massive that's 10mm over 100mm.

First thing was the bottom of the vice clean so the material was sitting flat?

Also was the material sitting on the support at the other side of the blade from the vice.

Did you get hold of the blade frame and give it a good pull about to feel for play?

 

[Shox Dr]

Cutting box section with too much pressure will cause this to happen

 

[scott0031]

On a hack saw it nearly always one thing ' blade' If i am reading this right and you are saying the cut looking from above to the floor is out, then its blade. It may look good nick but that does not mean it is. When the 'set' starts to go on any blade and is also blunting the effect is what you described, Other options are the work was not flat on the bed of the vice. If you are talking about the cut being out of square to the length of the material then the vice is our of square. This is all on the assumption there is not a ton of play in the frame slide. There is not a lot to go wrong and are very basic creatures. Most problems can explained away with the above



Kind regards


Scott

 

[Thrashsmith]

Cheers for the replies.

First thing was the bottom of the vice clean so the material was sitting flat?

Yes.

Also was the material sitting on the support at the other side of the blade from the vice.

There wasn't a support, just the vise and blade.

Did you get hold of the blade frame and give it a good pull about to feel for play?

There was barely any play, if any really.

Here's a pic of the saw...

 

[brightspark]

is there any wear on the vice bed . there was on mine and i built it up with weld and ground back level . check theres no slop on the guide bars and nip the 4 nuts up slightly if there is . then fit a new blade if it still cuts slightly off u can pack under one side of the frame to the guide bar with some shim to improve the acuracy

 

[Thrashsmith]

I couldn't see anything wonky or any wear so maybe I should ask him if I can view it again and test a new blade on it as he had a couple spare. I've got a scrap galore at my workshop so maybe I should take a few different profiles to try on it and see how it fairs.

There wasn't any coolant on these demo cuts but I can't imagine that would make such a huge difference.(?)

 

[brightspark]

I couldn't see anything wonky or any wear so maybe I should ask him if I can view it again and test a new blade on it as he had a couple spare. I've got a scrap galore at my workshop so maybe I should take a few different profiles to try on it and see how it fairs.

There wasn't any coolant on these demo cuts but I can't imagine that would make such a huge difference.(?)

the only thing coolant does is keep the blade and job cool .cut easier less friction and make the blade last longer

 

[Fazerruss]

I would check the blade holders in the bow. Mine were stripped and so not holding the blade to prevent twisting. Mine now cuts better than my brothers Qualters and Smith after I gave it some TLC

 

[brewdexta]

my rapidor cut like this until I put some shims under the brackets that hold the arms in place, works lovely now.

Cheers
Andy

 

[Fazerruss]

This thread is going to bring out all the rapidor lover's.
Mattf will be here next
And remember a Rapidor is for life not just until Christmas!

 

[Maker]

If the price is good then it's defiantly worth buying it, even if it needs lots of work (not that it looks like it does).

 

[brightspark]

rebuilt from scrap all bearings re made guide bars reground frame was broken and re welded vice base built up and ground new vice clamping bar made ect 40 years. ago still mint

 

[Maker]

Very nice, Brightspark.

 

[Thrashsmith]

How tight should the blade be?

The guy's asking around the £100 mark which I think it a fair price for my region of the country, but it does sound like there's a variety of things that could be the problem and I don't know if I fancy a punt and a project at the minute.

 

[brightspark]

How tight should the blade be?

The guy's asking around the £100 mark which I think it a fair price for my region of the country, but it does sound like there's a variety of things that could be the problem and I don't know if I fancy a punt and a project at the minute.

the blade just needs a bit of tension on it not much looks a good price for a ton just have a quick look over as long as the bearings arent sloppy and check the crankpin for wear and see iff the guide bars have wear lines down them .if alls reasonable buy it u wont regret it . mines a workhorse so it just gets powerwashed off when it gets grimy and a coat of hamerite lashed over to keep it clean ish

 

[MattF]

This thread is going to bring out all the rapidor lover's.
Mattf will be here next
And remember a Rapidor is for life not just until Christmas!

One hates to disappoint.

As already mentioned, there's not much can cause a skewed cut other than the bow being off kilter else something blade related. Shims or a new blade will pretty much sort either of those problems. To check the bearing/bush, (there's only one, on the shaft which goes from the large pulley to the crank arm), just whip the belt off and see if you have any side or upwards movement when you wiggle the large pulley. There'll likely be some slight amount, but if you can see notable movement, the bronze bush/bearing will need replacing.