in need of a formula asap

Jul 2019
4
0
UK
Hi, I am for all intents and purposes New here, I have an issue where I am designing and making a full scale guillotine prop.
My question is
taking gravity as the driving force of one object in motion, how far from a dead switch would the second moveable object have to be to fall at the same speed as the first object in motion?
i have designed many stunts in my time and I tend to use the trial and error method of making something work, usually using crash dummies and sand bags, but this one requires unadjustable mechanisms, so it would require several rebuilds to work in this manor. Unfortunately, time and budget doesn't allow in this instance;
it is kind of a crucial calculation, as decapitation is kinda undesirable.
thanks in advance.
Madmad Geoffers Esq...
 
Last edited by a moderator:
Jun 2019
493
262
USA
I don't quite get what you're asking. Could you draw a diagram to make it clearer?

Also, I want to make sure you're not relying on two things to fall at the same rate to stop the blade. If it's just to hide the illusion, that's one thing, but no sane engineer or magician would OK a device where a slight misalignment or small amount of friction could potentially lead to decapitating someone. PLEASE make sure a competent engineer looks over your design before any human gets anywhere near it.
 
Jul 2019
4
0
UK
Hi dude
no the blade is both retractable and blocked from any potential contact from skin via a steel sheath, the two objects falling are to hide the ilusion predominantly, the steel sheath can be locked off so as to slice fruit for effect via a mechanical switch, my problem lies with both objects falling disjointed at the minute, the decapitation bit was for dramatic effect only to encourage an answer to be honest
thanks
MMG
 
Jul 2019
4
0
UK
i will try add design drawings sometime on wednesday when i am back in the workshop
thanks
MMG
 

skipjack

Forum Staff
Dec 2006
21,482
2,472
Typically, the guillotine is real, but can't operate until the real head has been replaced by a prop.
 
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Jul 2019
4
0
UK
IMG_20190805_220415.jpg

IMG_20190805_220451.jpgok so this is a quick plan sketch which shows all relevant info, the question is in the question marks thanks in advance MMG