OT Electric Domestic Oven Adaption

[Palindr☻me]

Hi,
I am a member of a local voluntary group of mostly engineers
who design and produce and donate specialist one-off
mobility aids for the elderly and disabled. They have just
been asked about modifications to a domestic, electrical
oven - so they naturally passed it to the female electrical
engineer in the group...

Basically, what is needed is for the two shelves of the oven
to be capable of sliding out their full length, whilst
supporting the weight of what may be a large turkey, without
sagging and with nothing normally protruding beyond the
normal mechanical envelope of the oven.

I can't think of what electrical engineer has to do with
this - hence the OT - but any thoughts on solutions, no
matter how off the wall, would be welcome. There are clearly
some very bright cookies lurking around this group...


My present thought is to put wheels on the sliding trays and
run them on tracks fitted into the oven and with extension
tracks that can be clipped on by the user when the oven door
is open. By mounting the front of the permanent track on an
offset bracket, the load pushing it down and hence slightly
forward would be translated by a lever into offsetting the
rear track bracket, to move the rear of the track forward
and slightly more lower. A small spring would pull it back
to the normal position when unloaded. Thus, as the tray
slides out so that its entire weight and leverage is applied
to the front bracket, the rear bracket will pull the back of
the rail lower - thus producing a slightly uphill gradient
for the tray, which will get even more uphill the more
weight on the tray. This should be enough to counter the
bending (non-permament) of the extended rail with the
applied weight.

Any alternative thoughts, or suggestions of more appropriate
groups?

I had thought of using the ball-bearing heavy-weight drawer
slides from surplus electronic equipment racks - but somehow
don't think that they would cope with the conditions in a
cooker..They do do wonders for drawers in kitchen cupboards
though..



Many thanks,

Sue

 

[SQLit]

Hi,
I am a member of a local voluntary group of mostly engineers
who design and produce and donate specialist one-off
mobility aids for the elderly and disabled. They have just
been asked about modifications to a domestic, electrical
oven - so they naturally passed it to the female electrical
engineer in the group...

Basically, what is needed is for the two shelves of the oven
to be capable of sliding out their full length, whilst
supporting the weight of what may be a large turkey, without
sagging and with nothing normally protruding beyond the
normal mechanical envelope of the oven.

I can't think of what electrical engineer has to do with
this - hence the OT - but any thoughts on solutions, no
matter how off the wall, would be welcome. There are clearly
some very bright cookies lurking around this group...


My present thought is to put wheels on the sliding trays and
run them on tracks fitted into the oven and with extension
tracks that can be clipped on by the user when the oven door
is open. By mounting the front of the permanent track on an
offset bracket, the load pushing it down and hence slightly
forward would be translated by a lever into offsetting the
rear track bracket, to move the rear of the track forward
and slightly more lower. A small spring would pull it back
to the normal position when unloaded. Thus, as the tray
slides out so that its entire weight and leverage is applied
to the front bracket, the rear bracket will pull the back of
the rail lower - thus producing a slightly uphill gradient
for the tray, which will get even more uphill the more
weight on the tray. This should be enough to counter the
bending (non-permament) of the extended rail with the
applied weight.

Any alternative thoughts, or suggestions of more appropriate
groups?

I had thought of using the ball-bearing heavy-weight drawer
slides from surplus electronic equipment racks - but somehow
don't think that they would cope with the conditions in a
cooker..They do do wonders for drawers in kitchen cupboards
though..

My first thought. The ones I have for my drawers are all metal with metal
ball bearings.
A quick google and then some phone calls to the manufactures will get the
answer. Heck they may even donate them for your cause. The total weight
will determine the distance you can go. My drawer slides go 18 inches at 75
pounds total. A turkey has some serious center of gravity issues.
http://www.usindustrialfasteners.com/

Not the glitziest web page. You MUST have pdf enabled to see the pages. They
are friendly and helpful. Yep also close to where I live. At least you
will have something to look at and ponder until the phones work on Tuesday


You realize that the shelves will be come fixed vertically doing this. That
in itself might be a deal breaker.

 

[Palindr☻me]

My first thought. The ones I have for my drawers are all metal with metal
ball bearings.
A quick google and then some phone calls to the manufactures will get the
answer. Heck they may even donate them for your cause. The total weight
will determine the distance you can go. My drawer slides go 18 inches at 75
pounds total. A turkey has some serious center of gravity issues.
http://www.usindustrialfasteners.com/

Not the glitziest web page. You MUST have pdf enabled to see the pages.They
are friendly and helpful. Yep also close to where I live. At least you
will have something to look at and ponder until the phones work on Tuesday


You realize that the shelves will be come fixed vertically doing this. That
in itself might be a deal breaker.

Thanks for that! I will see what they say - as you mention
they are friendly they may indeed be helpful rather than
just fall about laughing.

My present thought is to actually only fit one set of rails
at the very bottom of the cooker but provide a few different
height lift-off spacers (much as most microwave ovens are
supplied with) that can be placed over the bottom tray to
give multipe layers. It is a fan oven, so positioning within
the oven is not that much a factor.

Someone in another forum has suggested using an oven with an
open-down door and mounting the continuation rails in the
inside of the door - so that as the tray runs forward on its
rails, it can continue to run forward on rails on the door.
It seems a very simple and elegant solution - I wonder why
they don't fit them? It may need little drop-in bridging
pieces to join up the rails - but that should be trivial to
design and make.

 

[SQLit]

--------------------------cut------------------------------

My first thought. The ones I have for my drawers are all metal with metal
ball bearings.
A quick google and then some phone calls to the manufactures will get the
answer. Heck they may even donate them for your cause. The total weight
will determine the distance you can go. My drawer slides go 18 inches at 75
pounds total. A turkey has some serious center of gravity issues.
http://www.usindustrialfasteners.com/

Not the glitziest web page. You MUST have pdf enabled to see the pages. They
are friendly and helpful. Yep also close to where I live. At least you
will have something to look at and ponder until the phones work on Tuesday


You realize that the shelves will be come fixed vertically doing this. That
in itself might be a deal breaker.

Thanks for that! I will see what they say - as you mention
they are friendly they may indeed be helpful rather than
just fall about laughing.

My present thought is to actually only fit one set of rails
at the very bottom of the cooker but provide a few different
height lift-off spacers (much as most microwave ovens are
supplied with) that can be placed over the bottom tray to
give multipe layers. It is a fan oven, so positioning within
the oven is not that much a factor.

Someone in another forum has suggested using an oven with an
open-down door and mounting the continuation rails in the
inside of the door - so that as the tray runs forward on its
rails, it can continue to run forward on rails on the door.
It seems a very simple and elegant solution - I wonder why
they don't fit them? It may need little drop-in bridging
pieces to join up the rails - but that should be trivial to
design and make.



the door opens down the rails would have to be flexible, to change direction
as the door goes from vertical to horizontal. or up you would end up with
an slanted rail that would surely unload the "turkey" by gravity.

I really do not understand that concept at all.

 

[[email protected]]

I had thought of using the ball-bearing heavy-weight drawer slides from
surplus electronic equipment racks - but somehow don't think that they
would cope with the conditions in a cooker..

You might ask the manufacturer. Don't tell them you plan to modify it
as they will then stop talking to you, but ask if they have any kits to
do what you want. I know that many US manufacturers offer Braille
knobs or different handles for their appliances.

If that doesn't work, I think the drawer slides are your best option.
Find some slides that don't have any plastic pieces, and clean out the
grease (if any) with some not-too-nasty solvent like alcohol. You can
use them dry, but there is grease that is made to be used on machines
that process food. Talk to an oil company that supplies lubricants to
industry, or perhaps go down to the local bakery, brewery, or meat-packing
plant and offer to buy the maintenance guy lunch in exchange for a few
grams of grease. A quick Google yields
http://www.superior-industries.com/index/articles_view.php/id/67 which
looks like it might do what you want.

You might have to narrow the shelf a bit to get it to fit in between the
slides.

Standard disclaimers apply; I don't get money from any of the companies
mentioned above.

Matt Roberds

 

[Palindr☻me]

--------------------------cut------------------------------


Thanks for that! I will see what they say - as you mention
they are friendly they may indeed be helpful rather than
just fall about laughing.

My present thought is to actually only fit one set of rails
at the very bottom of the cooker but provide a few different
height lift-off spacers (much as most microwave ovens are
supplied with) that can be placed over the bottom tray to
give multipe layers. It is a fan oven, so positioning within
the oven is not that much a factor.

Someone in another forum has suggested using an oven with an
open-down door and mounting the continuation rails in the
inside of the door - so that as the tray runs forward on its
rails, it can continue to run forward on rails on the door.
It seems a very simple and elegant solution - I wonder why
they don't fit them? It may need little drop-in bridging
pieces to join up the rails - but that should be trivial to
design and make.



the door opens down the rails would have to be flexible, to change direction
as the door goes from vertical to horizontal. or up you would end up with
an slanted rail that would surely unload the "turkey" by gravity.

I really do not understand that concept at all.

No, that is where the bridging pieces come in. There would
be fixed rails on the bottom of the oven and fixed rails on
the inside of the door. When the door was full open the
rails would line up but there would be a gap between the
bottom rails and the door rails - the bridging pieces would
bridge the gap. As the wheels on the tray came out of the
oven, then would initially be running on the bottom rails,
then the bridging pieces and then the door rails.

 

[Palindr☻me]

You might ask the manufacturer. Don't tell them you plan to modify it
as they will then stop talking to you, but ask if they have any kits to
do what you want. I know that many US manufacturers offer Braille
knobs or different handles for their appliances.

If that doesn't work, I think the drawer slides are your best option.
Find some slides that don't have any plastic pieces, and clean out the
grease (if any) with some not-too-nasty solvent like alcohol. You can
use them dry, but there is grease that is made to be used on machines
that process food. Talk to an oil company that supplies lubricants to
industry, or perhaps go down to the local bakery, brewery, or meat-packing
plant and offer to buy the maintenance guy lunch in exchange for a few
grams of grease. A quick Google yields
http://www.superior-industries.com/index/articles_view.php/id/67 which
looks like it might do what you want.

You might have to narrow the shelf a bit to get it to fit in between the
slides.

Thanks Matt. I actually have some heavy duty drawer slides
(the type with an intermediate slide so the drawer can be
extended completely out of the carcass). They are all-metal
with no plastic. My only worries are the lubricants that
will take 350 deg C. The oven sides get much hotter than the
set temperature because that is where the heating elements are.

I can easily weld up some new trays to fit and get them
chrome plated at a local shop that does such things.

I will have a go at yellow pages for the oil company
references but lubricants aren't my field at all!

 

[John G]

No, that is where the bridging pieces come in. There would be fixed
rails on the bottom of the oven and fixed rails on the inside of the
door. When the door was full open the rails would line up but there
would be a gap between the bottom rails and the door rails - the
bridging pieces would bridge the gap. As the wheels on the tray came
out of the oven, then would initially be running on the bottom rails,
then the bridging pieces and then the door rails.

Just looked at my oven, made in Australia, but principle should be much
the same.
Door opens down and is almost flat with bottom of oven when right down.
If there was a set of rails on the bottom of the oven and another set on
the door with just enough gap to clear the opening and closing, then the
tray could have 2 sets of wheels or slides close to the front edge and
that would allow it to bridge the gap without putting pieces in.
For the number of movements and the relatively small weight slides with
no rotating parts and no lubrication, might be enough.

 

[Peter]

Depending on how creative you get, you could probably find a dozen or more
solutions to this problem. I have to agree that using a heavy-duty set of
steel rails (Like the kind you find in heavy-duty filing cabinets) is
probably the best idea. You are correct in worrying about the lubricants
though. Here is another solution to deal with that. Have you considered
replacing the steel wheels with solid teflon wheels? Then you could
eliminate liquid lubrication altogether.

I know, this is the point where most people say, "Yeah right. Where on earth
am I supposed to find solid teflon wheels!?" Good question. There are two
possibilities that come to mind. Some time ago I found a place on the
Internet that sold me the solid teflon balls that I needed for a project. I
don't remember their name, but mention it only to prove the point that solid
teflon parts are available commercially. They weren't very expensive either.
I think I paid about $20 for 50 of them. If that doesn't pan out, there is
always custom fabrication. In most cases this would be cost prohibitive, but
it just so happens that my father is a retired machinist with a lathe and a
surplus of old teflon parts in his garage. He may get a kick out of a
project like this. (Disclaimer: I haven't asked him yet.)

If the latter sounds interesting, drop a line in this thread and I'll let
you know how to get in touch with me. Good luck on your project!

-Peter P.

 

[TimPerry]

Thanks Matt. I actually have some heavy duty drawer slides
(the type with an intermediate slide so the drawer can be
extended completely out of the carcass). They are all-metal
with no plastic. My only worries are the lubricants that
will take 350 deg C. The oven sides get much hotter than the
set temperature because that is where the heating elements are.

I can easily weld up some new trays to fit and get them
chrome plated at a local shop that does such things.

I will have a go at yellow pages for the oil company
references but lubricants aren't my field at all!

seems like any sliders with ball bearings will soon get gummed up inside an
oven. what about a fork lift device that reaches into the oven picks up the
turkey, elevates it to table or counter height and sits it down again?

or maybe a simple adjustable height tray on wheels with a hook and winch to
slide the turkey on to it.

 

[Roy Q.T.]

I like the miniature fork lift idea !

A modified small AC lift *Table, [* not sure if that's what they call
em?]

Think about it };-) They won't have to bend down to the oven too long to
baste and whatever else is done to turkeys and heavy baked goods .....
it could be lifted right up to them., rolled over to the table and
served yumm

I've seen some pretty snazzy electric carts with wired controls you can
probably modify as well., money is a matter?
why am i not a millionaire oh well

You get some weird challenges Sue

buena suerte

 

[robert grant]

QED. Filing cabiner steel cabinet runners!ok

 

[[email protected]]

Hi,
I am a member of a local voluntary group of mostly engineers who
design and produce and donate specialist one-off mobility aids for the
elderly and disabled. They have just been asked about modifications to
a domestic, electrical oven - so they naturally passed it to the
female electrical engineer in the group...

Basically, what is needed is for the two shelves of the oven to be
capable of sliding out their full length, whilst supporting the weight
of what may be a large turkey, without sagging and with nothing
normally protruding beyond the normal mechanical envelope of the oven.

I can't think of what electrical engineer has to do with this - hence
the OT - but any thoughts on solutions, no matter how off the wall,
would be welcome. There are clearly some very bright cookies lurking
around this group...


My present thought is to put wheels on the sliding trays and run them
on tracks fitted into the oven and with extension tracks that can be
clipped on by the user when the oven door is open. By mounting the
front of the permanent track on an offset bracket, the load pushing it
down and hence slightly forward would be translated by a lever into
offsetting the rear track bracket, to move the rear of the track
forward and slightly more lower. A small spring would pull it back to
the normal position when unloaded. Thus, as the tray slides out so
that its entire weight and leverage is applied to the front bracket,
the rear bracket will pull the back of the rail lower - thus producing
a slightly uphill gradient for the tray, which will get even more
uphill the more weight on the tray. This should be enough to counter
the bending (non-permament) of the extended rail with the applied weight.

Any alternative thoughts, or suggestions of more appropriate groups?

I had thought of using the ball-bearing heavy-weight drawer slides
from surplus electronic equipment racks - but somehow don't think that
they would cope with the conditions in a cooker..They do do wonders
for drawers in kitchen cupboards though..



Many thanks,

Sue

Anything you add to the inside of the oven will need
to survive repeated delta T without deforming etc.
Wheels will gum up at the axel and the wheel hub/axel
will expand/contract due to delta T. You really need a
simple, cheap, no moving parts solution.

If the oven in question is not already built with the
following design (or a variation) this may help:
The addition of one stud to each side of the oven near
the front may be what you need. "Drawn" below is the
existing oven tray with the added stud:

___________________________0______
=== === === ===

=== are oven "bumps" or "rails" that the existing tray
rests on and 0 is the stud. You could weld a lip to
the rear of the tray such that it can't slide beyond the
stud unless the front of the tray is lifted. There will be significant
force against the stud with the tray fully
extended, so how you mount it is important. Make it STRONG.
I would affix a backing plate. By the way, I always assumed
that this is the way most ovens are built to begin with, but
your post got me thinking that perhaps that is not true.

You lose a couple of inches of your requirement (that the
tray slide all the way) with the above proposed solution, as
the loaded tray cannot be pulled out beyond the stud. So - is sliding
the tray out where all but about 4 inches sticks
out workable and useful? Is the oven in question already
made that way? (It should be, in my opinion.)

That brings us to plan B. Instead of modifying the
oven with parts that would be subjected to large
delta T, how about an external transfer rack? You
bring it to the oven, slide the oven tray out part
way or all the way - whatever works - then slide the
turkey off the oven rack onto the transfer rack.

The transfer rack can be a hinged affair with wheels
so that when in operation it looks like a table, but
it folds up for storage. The rack that receives
the turkey would be removed for washing and to allow
the thing to fold. H in the "diagram" below is the
hinge. The washable rack would drop in at the proper
height, locking the unit into a rectangular shape:



..| .|
.. | . |
| | | |
| | | |
| |--------| |
|---- rack----| |
| | | |
| |--------| |
| . o | . o
H-------------H
o o


Are you by any chance associated with the group in Swindon
that helps disabled folks? When I was devising a window
opener for a disabled friend I contacted them. They do
some very clever things! If you are not associated with
them already, they might be able to help.

Ed