There are a few main things to consider when buying a Home gym/Smith Machine and you should be aware of them all before making your final purchasing decision.
• The Exercises You Intend To Do
You need to decide exactly what you want from your equipment. The cheapest home gyms offer fewer stations than the more expensive models. A small, cheap multigym often has a short bench which makes an exercise like double leg curls impossible and forces compromise on many other exercises whilst something like a pec dec is typically only available on the more expensive equipment.
• Can You Fit On It?
It might sound like a silly question but can you? Many home-gyms with non-adjustable seating are designed for people between the height of 5' 8" to 6' 2" and if you happen to fall outside of that height range you may find them uncomfortable to use. The same applies to people of larger girth, some multigym equipment have really narrow benches which will again cause discomfort and others leave very narrow gaps between the bars which may make the machine unusable for some. Remember also, a comfortable multi-gym for one person may be extremely uncomfortable for another and the only way you will know is to test it out before buying one.
• Who Else Will Use It?
If you are the sole person who will use your home gym then fine, buy what suits you best. However, if other members of the household will use it then you will be best advised to look around at the adjustable multi-gym machines out there. Look for a home gym with an adjustable back, seat and lifting bar. You also need to consider the weight limits and minimums and ensure they cover all levels now and give scope for future requirements. A minimum of around 10lbs and upper limit of 200lbs should suit most needs.
• What Exercises Do You Intend To Do?
Different multigyms offer many different stations (exercises) ranging from around 10 - 15 exercise routines to a few dozen. You need to decide which muscle groups you want to work on, what your future requirements may be and whether you can justify the additional costs of a full featured multigym. A good weights machine should allow around 12 different exercises at the minimum level without requiring adjustment.
• Space Requirements
How much room do you have? Manufacturers have redesigned many of these models to be more home-user friendly but the average multi-gym is still something of a bulky beastie. Also note that, unlike most cardiovascular exercise machines; many forms of muscular training performed on your multigym will require you to sit, lie or stand outside the footprint of the equipment so be sure to take that into consideration when deciding whether or not you have the space needed for a piece of equipment like this.
• Assembly Requirements
If you are looking for easy to assemble exercise equipment then a multi-gym is definitely not the best option for you. Expect to put aside half a day for the initial assembly of your home gym.
• Noisy Multigyms?
As a home user the chances are you will not want a weight lifting machine which sits there sqeaking, clanking and grinding throughout the entirety of your workout. You'll drive yourself, your family members and your neighbours insane within a mere few days. Fortunately, most home gym equipment comes with noise restriction of some form or another and weight machines are no different. Again, try the machine out yourself to see whether it fits your noise free requirements or not. Try to avoid pulleys which make a dragging noise and opt for smooth, quiet motion instead. Check out the frame thoroughly as well, you want a good solid frame rather than a shaky one which rattles horribly when you are using it.
• Construction Quality
As with any kind of exercise equipment, a smith machine made from high quality materials with good construction quality will require less maintenance and will ultimately last longer and be more pleasurable to use. As a layman there are a few things you can see straight away when comparing different multigyms. Pay special attention to the frame, particularly ensure the frame is made from quality materials (11 or 12 gauge steel is the norm), that welded joints are fully rather than patchily welded and that the protective finish is even and complete otherwise you will, potentially, notice early rusting and corrosion.
• Safety Considerations
Stability is an important consideration when purchasing a home gym. Physically shake the model you are thinking of buying to test whether the frame is of a sturdy construction. Yes, you are well advised to actually go out to the seller and test out the machine...don't buy something like this blind.
While you are there, check out the cables. Covered cables last longer and if you intend to lift heavy weights you should make sure they are able to take the strain.
Do you have young children in the house? If so you would be well advised to find a separate room for this machine if possible and keep it locked when you are not using it.