Author Topic: Scissor lift  (Read 3400 times)

Maker of Things

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Scissor lift
« on: November 11, 2013, 09:36:25 PM »
I have an installation to do, fitting a Georgian Mahogany corner cabinet.
Due to the weight and awkwardness of the job I wasn't keen to try and hold it up against the wall while drilling through the fixing holes in the back panel to put in fixings without some extra support.

As the client is uncertain how high up the wall she would like the cabinet I have decided to make a small scissor lift to raise and hold it in position.

I have a small collection of screw operated car jacks, some of which I use as adjustable stands in the workshop.  One of them will be used to drive the scissor lift.

The scissor bars of the lift are made from some laminated beech wood bed slats recovered from a scrap bed.  They are a little bowed but that won't matter as long as the bows are acting against each other in balance.  The pilot holes have been drilled at 14" centres giving 28" overall. 
M12 threaded rod (just because I found a bundle in a skip) will be used as the pivots of the scissors and each hole will be sleeved with some 12mm bore steel tube to reduce wear.

I will post more photos when I get some more of it built.
If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #1 on: November 12, 2013, 10:29:13 PM »
To reduce the wear on the wooden lift arms I decided to bush the holes with steel tube.
I had some off cuts off 12mm ID 14mm OD tube which I was able to cut with a plumbing pipe cutter.  The bushing was then pressed into the lift arms with a G cramp.

If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #2 on: November 12, 2013, 10:31:26 PM »
For the lift slides I found some pine that was from an old futon base I had recycled.
I bored three 14mm holes and then used my router table to mill a slot between two of the holes in each of the rails.
If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #3 on: November 12, 2013, 10:37:00 PM »
I did a quick test run of the lift action.
It works and extends 50" and is 10" when closed down.

Working it allowed me to measure the amount of lift screw I would need to operate it.
If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #4 on: November 12, 2013, 10:45:12 PM »
I used the old Land Rover jack for the screw.  Fortunately the jack was scrap as the screw had been bent but it would be ok for the scissor lift.  I 'leaned on it' a little, while it was held in the vice, to straighten the screw enough to make it usable.

The attachment points for the screw came from the legs of an old school table with a nut welded into each end.  The T shaped part needs to be braced for strength but was adequate for bench testing.
I will also need to make a handle for the square drive of the screw thread and then find some 'stuff' to make the top and bottom of the scissor lift table.

If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #5 on: November 13, 2013, 05:44:07 PM »
Today I did a bit more welding and braced the metalwork at both ends of the screw. I also welded an old 3/8" drive socket to the drive end of the screw so that a ratchet or drill/driver can be used to power it.

A couple of old cupboard doors and shelves from an old 70's sideboard were used to make the base and the table top.  These were glued and screwed in place.  A set of castors were then screwed to the base.

A test weight by way of 30kg of Jet 12" bench top thicknesser was placed on it and it successfully wound it up.

Using the drill at high speed makes it all wobble quite a lot due to the still not quite straight jack screw.


One annoying problem is that from flat to about halfway up the table top is free to lean side to side.  Above halfway up and the whole thing becomes much more rigid.
I suspect that it is the thinness of the scissor arms allowing them to flex.  Also it could be that there is very little torsional rigidity between the lift arms on each side so they are free to rise at different rates.

It will do for the job I built it for but I may start sourcing scrap materials to make a more rigid version.
If it ain't broke, you're not hitting it hard enough!

Maker of Things

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Re: Scissor lift
« Reply #6 on: November 15, 2013, 01:21:51 AM »
This is the reason for making the scissor lift.

The cabinet is an antique, heavy and awkward.  The walls are aircrete block and very soft.  The height was to be approved by the client.

The scissor lift make it so easy in the end and I was able to work without any stress or worry about the cabinet being at the wrong height, not level, or at risk of being dropped.

I am very happy with the result, as was the client. :)
If it ain't broke, you're not hitting it hard enough!

nikki

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Re: Scissor lift
« Reply #7 on: November 15, 2013, 05:06:11 PM »
You stuck it on with that masking tape?! That isn't going to stay up for long!  ;)


Saw bits of the build via Twitter - great to read about it in more detail and see the final/first application.

Maker of Things

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Re: Scissor lift
« Reply #8 on: November 15, 2013, 11:13:02 PM »
I used some expanding plug fixings that specified being suitable for aircrete.

I have read that big old wood screws work just as well but I wasn't sure I was ready to trust that without some testing experience.

I figured that on Twitter I was limited to 140 characters and so this seemed a good place to expand on the tweets.

I'd link to the threads but as the images don't show, unless logged in, there seemed little point.
If it ain't broke, you're not hitting it hard enough!

nikki

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Re: Scissor lift
« Reply #9 on: November 17, 2013, 12:11:21 AM »
I think I've sorted it so attachments show to guests now.

The other option is to upload somewhere (Flickr etc) and embed images into the body of the post (writing this I also notice attachments don't show up in the topic summary list below the bit where you type replies)


Maker of Things

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Re: Scissor lift
« Reply #10 on: November 18, 2013, 03:50:35 PM »
Thank you, Nikki, hopefully that will mean guests will take more interest as they can see what we are talking about.  :)
If it ain't broke, you're not hitting it hard enough!