Base clamp not locking RAB Stringmaster

[J-Wildcard]

I have a manual RAB Stringmaster 750 and unfortunately for a while now one of the two clamps are struggling to get a lock when the clamp is switched, this results in slipping sometimes but often just requires many attempts to get it to lock firmly and stay in place. Does anyone have any experience of this problem on this type of machine. I have uploaded a picture above to show the clamp type, it is the base clamp. Thanks for reading

 

[Dags]

Have you tried tightening them? You need to position the clamp at 90 degrees to the rail (so very close to where you are in the picture - just a little more anti-clockwise), then insert an allen key via the hole that is already exposed. Should be clockwise to tighten, anti-clockwise to loosen. You'll know pretty quickly... if you tighten too much, the clamp won't move up and down the rail.

 

[J-Wildcard]

Thanks for the advice, i have tried tightening them, i am not sure if it is maybe a 3 or 4mm key needed. Unfortunately the one i have only goes through about 4-5cm so based on the picture will only reach through as far as the top of where the RAB logo is. Am i right in thinking the adjustment point will be past that black sticker with the RAB logo on? Until I source a longer Allen key i cannot try this.

 

[ElMagoElGato]

You need a 3 mm Allen wrench and a longer one. You might be interested in my thread about it.

https://tt.tennis-warehouse.com/index.php?threads/maintain-eagnas-spring-assisted-clamp-base.578137/

 

[Dags]

Yes, it goes right into the base, and has to be in alignment to reach the screw (hence the 90 degrees angle to the rail).

I got a few allen keys with the machine, so for me it's always just been 'the one that fits'. I think I have another set of allen keys with the size on them: happy to check which one you need if required.

 

[J-Wildcard]

Yes, thank you for the replies again. I will try this as soon as i get a longer Allen key, sounds likely it will be a 3mm then? Both clamps feel very similar to move around so not excessively loose or tight, about right but internally if this adjustment can be made via lining up at 90 degrees with Allen key then all being well. I find it gets a good lock sometimes but then other times it gets no good lock at all so it is just performing very inconsistently. I had tried adjusting the 2 screws either side of the clamp lever but as i understand they just trap a bolt going through which hold the spring in place for the lever which is used to clamp and unclamp.

 

[J-Wildcard]

I have tried it earlier today with a longer length 3mm key and it seems to have done the job and stopped it slipping i guess i can fine-tune it to get a balance, hopefully it will hold up as it is but definitely seems to be sorted out now. Thank you for the help

 

[Dags]

I occasionally have to readjust mine. You'll notice that when it's tightened, there's less travel in the lever on the base clamp. Over time, this seems to increase slightly, until you reach the point you experienced where it starts slipping. I usually check it when I clean my clamps now. Fortunately, it's very straightforward to fix when you know how.