What's new
What's new

Infratirea oradea FUS-22 Deckel Clone milling machine backlash on X-axis

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
Hi
I have a problem with my FUS-22 milling machine. It has severe backlash on the x-axis, about 5mm, more than can be accounted for by wear. Maybe something is missing or broken. I suspect there should be a bush between the left X handle and the table. If there is, I don't know what it should be.

If anyone has access to a 1975 vintage FUS-22, could they tell me what I might be missing. I have attached photos of my machine of the left X handle to illustrate the problem.
IMG_1367 (1014 x 760).jpgIMG_1368 (1014 x 760).jpg
I have also attached a rather blurry photo of a machine that looks like it has a bushing where I don't.
fus22 handle.png

I have the manual but it doesn't include enough detail to figure what should be there.

Any help appreciated.
 

PDW

Diamond
Joined
Jul 24, 2006
Location
Australia (Hobart)
I have one of those and IIRC the LH handwheel does have a lot of play - it's spring loaded not to engage all the time I think. You need to push it across to get it to actually move the screw & table. So I don't think this is your problem. Happy to take a look at mine tomorrow if you want to post more/better pix but I'm pushed for time this week so can't do a lot really if it involves any disassembly.

Mine has very little backlash.

Interesting that you have one, they seem to be quite rare beasts. I got mine with the box table, angle table, slotting head and high speed head as well as the regular 40 taper vertical head. It's a really nice little mill. Only complaint I have is insufficient Z height.

PDW
 

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
Hi
Thanks for the quick response.
My LH hand wheel has a LOT of play. One full turn.
All of my hand wheels are connected all the time. No spring to disengage.

I found a photo in a brochure I have. It shows no bushing where I thought one might be missing. This means my problem must be internal and out of sight. Something inside is probably bent, broken or missing.
I have the angle table, regular 40 taper head, high-speed head, and the slotter (really useful). It was also purchased with a number of factory tooling options.
I don't have the horizontal arbor. I will have to make one.

It is a nice mill that I waited 5 years for the previous owner to sell. I agree, Z is short.

I will take the table and X-axis apart to look inside. I am hoping to find something obvious. It will give me a chance to do a deep clean/lube. That will probably take me a week or three to get done due to other commitments.
 

AlfaGTA

Diamond
Joined
Dec 13, 2002
Location
Benicia California USA
There are two ways to transmit motion of the screw to the table.....
!. Must have a double thrust setup (washers or bearings on each side of the moving part (table end plate))
2, Or a thrust washer(plain or anti friction) at each end of the screw.(table end plates)
In method one there is some method of adjusting the space between the thrust washers...usually the screw is threaded and a set of adjusting and lock nuts used....
In method 2, the end of the screw is threaded on the end and an adjusting nut and lock nut used to work the bearings at each end of the table against each other.

Generally setup 1 is preferred as it removes any problems of differential thermal expansion between the screw and the table. In this setup the outer end of the table has a bearing or bushing to support the screw, but it is not in tension with the opposite end bearing....It is just floating axially. This is how Deckel does their "X" axis table setup.

Cheers Ross
 

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
There are two ways to transmit motion of the screw to the table.....
!. Must have a double thrust setup (washers or bearings on each side of the moving part (table end plate))
2, Or a thrust washer(plain or anti friction) at each end of the screw.(table end plates)
In method one there is some method of adjusting the space between the thrust washers...usually the screw is threaded and a set of adjusting and lock nuts used....
In method 2, the end of the screw is threaded on the end and an adjusting nut and lock nut used to work the bearings at each end of the table against each other.

Generally setup 1 is preferred as it removes any problems of differential thermal expansion between the screw and the table. In this setup the outer end of the table has a bearing or bushing to support the screw, but it is not in tension with the opposite end bearing....It is just floating axially. This is how Deckel does their "X" axis table setup.

Cheers Ross
Hi
I think my mill uses a single nut.
The nut is almost split with narrow slots
When confined, the nut is compressible to reduce the backlash.


This is explained in more detail in a document I found on-line.

. fus22 nut.png
BIMETAL EXTENSIBLE NUTS CONSTRUCTION
NAGY Alexandru1, MIHAILA V, Ioan2
1SC Gazex Trade SRL, 2
University of Oradea
The technology refers to the bimetal extensible nuts construction for generalpurpose milling machines for tool-room FUS 22, FUS 25, FUS 32. These machines are intended for the performance of milling cut operations in the tool-rooms, as well as in the series production. The kinematics of the said machines assures the execution of a large range of cutting operation in optimum conditions. The speed, feed and generally, the entire machine operation is easy and accurate due to the used mechanisms.
The extensible nut is coupled with the driving spindle of the feed mechanism of moving towards the longitudinal direction of the table. The trapezoidal thread of the nut is matched with the hardened and rectified thread of the driving spindle. During the operation, due to the frictions between the extensible nut's flanks and the driving spindle it is taking place a nut's wear in time, which leads to a clearance between the nut and the spindle. In order to eliminate this inconvenience there has been provided a system of removing the clearance between the nut and the spindle. The nut is slotted in the middle by three milled channels at 2 mm width, at 6 mm distance and a depth equal to 80% of the nut's diameter. This nut is introduced into a cylindrical box where it can be axially preloaded with the help of a special nut. Therefore by clamping or by tensioning the extensible nut with the help of the special nut there takes place its axial deformation, removing the fitting clearance resulted from wear.
In order to assure the lubrication level, as well as the quality of the surface which has a direct influence on the wear and on the screwed fitting behavior during operation, the said nuts are made from superior bronze.
The disadvantages of this nuts are:
− reduced safety and durability in operation, due to the slotted area; − large bronze consumption dictated by structural form; − reduced elasticity due to section's thickness of the slotted part, which besides elasticity must also assure resistance;
− high percentage of waste due to the slotted area which directly influences the mechanical properties of the nut where any structural or casting defect leads to part's rejection.
The extensible nuts construction in accordance with the technology eliminates these disadvantages by making the nut's body out of rolled steel and the thread executing in the deposited bronze by centrifugal plating. Therefore, the nut is divided into three areas, out of which two areas are from plated bronze where the thread is cut and an area slotted between the two screwed areas which is made only from steel which assures the nut extensibility.
The steel support in the case of the nuts from the product FUS 25 and FUS 32 are made of tubes OLT 35; and in the case of the nuts from FUS 22 are made from bar because the STAS does not stipulate tubes with adequate walls' thickness. In both cases the steel support, in view of plating is processed in interior at a diameter which assures a bronze shell under the thread of equal thickness to the half of the thread pitch.


I will need to take my drive apart to see if I have this nut fitted, and if it is OK.
 

PDW

Diamond
Joined
Jul 24, 2006
Location
Australia (Hobart)
I had a quick look at mine today, the LH handwheel is definitely spring-loaded out of engagement, you have to push in & hold it there to move the table. Sort of always made sense to me because you operate the machine from the RH side and that handwheel has the graduated dial etc on it. The LH one doesn't.

So it's apparent some details between your machine & mine differ, not helpful I'm afraid.

PDW
 

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
I had a quick look at mine today, the LH handwheel is definitely spring-loaded out of engagement, you have to push in & hold it there to move the table. Sort of always made sense to me because you operate the machine from the RH side and that handwheel has the graduated dial etc on it. The LH one doesn't.

So it's apparent some details between your machine & mine differ, not helpful I'm afraid.

PDW
Thanks for taking the time to look.
Looking at FUS-22 on the Interweb, I see subtle differences with age. I will need to pull mine apart to see what I have.
 








 
Top