Festool Clamps losing "grip"

[transatlantic]

Is anyone else having trouble with the Festool screw clamps sliding (the part shown in red in the image below) when they're being screwed down? I have a 6 of them now, and 3 of them simply have stopped working. Two of them slide as soon as you start to apply any pressure from screwing down and the other one will clamp ok-ish, but then fail as soon as it gets bumped or there is any vibration.

 

[Argus]

Most of the 'F' clamps that I have, both cheap and expensive, develop this problem sooner or later.

They work on the amount of friction generated by the lateral pressure of the clamp at that point on both sides of the vertical bar. In use this bar gets smooth or glazed over and the clamp section then moves under pressure.

One fix that seems to work is to introduce some form of roughness on both sides of the bar with a hack-saw or very rough file. Sounds drastic, but it works. When new, you'll probably notice that there is a series of serrations in this part....... it's this that needs tarting up.

If you use bench hold-fasts (which work on the same principle) you'll get the same problem which can be overcome by popping a series of pock marks on the back of the bar where it jams in the bench with a centre-punch.

Hope this helps

 

[galleywood]

I had problems with these clamps when using them to hold down my track saw guide rail.
It was resolved when I realised that the 'L' shaped part was pressed hard up against the MFT style work surface.
Backing this off allowed the clamp to equalise and then clamped OK.

 

[DBT85]

Not got any of the Festool ones but the cheap ones I bought had one like it out of the box. A file and 2 minutes to file some lines on one face and the problem was solved.

 

[transatlantic]

When new, you'll probably notice that there is a series of serrations in this part....... it's this that needs tarting up.

Oddly they don't have serrations. It's smooth on both sides. But then so are my Axminster ones and they work just fine.

 

[Cabinetman]

Exactly what Argus said, they recommend you use some very rough sandpaper to create scratches going around i.e. not up and down the shaft on holdfasts. And it does work. Ian
Ps you haven’t been cleaning them with WD-40 or anything have you?

 

[transatlantic]

Ps you haven’t been cleaning them with WD-40 or anything have you?

Nope.

I'll try filing them and see if it helps. but looking at them, they're smooth all the way down. There is no sign of wear or change from the areas that never get used (towards the bottom)

Here is a good shot showing just how smooth they are :

I don't see why some are working and others are not. They all look the same as far as I can tell.

 

[Argus]

As an experiment, make a few lateral file or saw marks straight across the back and front for an inch or so on one of them in the spot where it slipped and see if there's an impoverishment.
I've not come across that make. Are they expensive?

 

[transatlantic]

As an experiment, make a few lateral file or saw marks straight across the back and front for an inch or so on one of them in the spot where it slipped and see if there's an impoverishment.
I've not come across that make. Are they expensive?

You've not come across Festool? They're usually about £25 for a pair.

 

[Argus]

£25 is that expensive?
Seriously, I haven't bought any tools for donkey's years. My stuff is covered with old name stamps.

I got most of mine off a bloke who was giving up chopping wood to join a circus..... Chipperfield, or Chippendale I think he said his name was...... Chippy-something, anyway!

 

[Rorschach]

I have these and while they in general are very good, I do need to be careful about how I use them. I think it's because they clamp along the entire face rather than just the tip as it would be on a normal F-clamp. This means that if I get them a bit skewed they seem to clamp fine but quickly lose their grip. If I set them carefully though they work fine.

 

[Argus]

................................... I think it's because they clamp along the entire face rather than just the tip as it would be on a normal F-clamp. This means that if I get them a bit skewed they seem to clamp fine but quickly lose their grip. If I set them carefully though they work fine.

That's an interesting point: most 'F' clamps have a 'foot' on the solid bar that aligns with the screw-pad.
Perhaps a pad of scrap wood in this area may improve the action - or at the least, proove if it slips or not. Perhaps the full contact along the bar prevents the potential of a pivot effect on the sliding bar.

 

[TheUnicorn]

I'd have expected better of festool

I think the points made about the pressure being spread too wide make sense, if there are no grooves on the shaft they shouldn't need them, though it might help.

 

[pcb1962]

I'd have expected better of festool

These clamps are a bit of an aberration in the Festool range, I think they expect that if you're a true believer you'll ignore these and fork out for the far superior version

 

[transatlantic]

I filed one of them down a bit and it did indeed help. However, I only had a fine file, so going to try and find something a little rougher. Any suggestions for something I can buy online?

 

[Andy]

I have some axminster ones that developed the same problem. I fixed the issue by drilling a series of 5 mm holes along the length of the shaft, say about an inch and a half apart. When I am clamping up I put an m5 bolt through one of the holes at the appropriate point on the shaft which prevents the clamp from slipping. This works very well and I expect the clamps to last a lifetime using this method.

 

[Doug B]

I’d have a word with Festool about it transatlantic, they are made by Bessey for Festool I’ve a couple of Bessey ones for my Festool track they’ve had plenty of use & still work fine & as the photo shows the shank is smooth.

 

[SamTheJarvis]

I filed the inside of the hole on the sliding part, figured the corner likely has to be somewhat sharp, and widening the hole would only increase the angle of attack. Worked for a while, then filed the grooves into the rail and has been fine since. Easily worth it over buying new.

 

[transatlantic]

Bit of an update on this.

Festool have agreed to replace all 3.

However I am still trying to fix them. I bought a very rough file and filed both sides of the main bar. This appeared to work great, but after about an hour or so of being clamped up, it fails ...

 

[TheUnicorn]

hopefully festool will still take them after your efforts with the file